Secure public cloud with protected guest-verified host control

ABSTRACT

According to one embodiment, a method comprises executing an untrusted host virtual machine monitor (VMM) to manage execution of at least one guest virtual machine (VM). The VMM receives an encrypted key domain key, an encrypted guest code image, and an encrypted guest control structure. The VM also issues a create command. In response, a processor creates a first key domain comprising a region of memory to be encrypted by a key domain key. The encrypted key domain key is decrypted to produce the key domain key, which is inaccessible to the VMM. The VMM issues a launch command. In response, a first guest VM is launched within the first key domain. In response to a second launch command, a second guest VM is launched within the first key domain. The second guest VM provides an agent to act on behalf of the VMM. Other embodiments are described and claimed.

This application claims priority to U.S. patent application Ser. No.15/444,771, filed Feb. 28, 2017; which claims priority to U.S.Provisional Patent Application Ser. No. 62/373,627, filed on Aug. 11,2016, with inventors David Durham, Ravi Sahita, Barry Huntley, andNikhil M. Deshpande, entitled “Secure Public Cloud.” Also, thedisclosures of those applications are hereby incorporated herein byreference.

TECHNICAL FIELD

Embodiments relate to security of a public cloud, and in particular,enabling a consumer of public cloud services to ensure that theconsumer's processes executing in the cloud and the consumer's privatedata are secured from access and modification by others, including thepublic cloud services provider.

BACKGROUND

The term “cloud computing” is used to describe network-based computing(typically over the Internet). According to Wikipedia, “cloud computingprovides shared processing resources and data to computers and otherdevices on demand. Cloud computing is a model for enabling ubiquitous,on-demand access to a shared pool of configurable computing resources(e.g., networks, servers, storage, applications and services), which canbe rapidly provisioned and released with minimal management effort.Cloud computing and storage solutions provide users and enterprises withvarious capabilities to store and process their data in third-party datacenters. Cloud computing relies on sharing of resources to achievecoherence and economy of scale, similar to a utility (like theelectricity grid) over a network.” (Source: Wikipedia,https://en.wikipedia.org/wiki/Cloud_computing, visited Aug. 11, 2016,citations omitted.)

The present availability of high-capacity networks, low-cost computersand storage devices as well as the widespread adoption of hardwarevirtualization, service-oriented architecture, and autonomic and utilitycomputing have led to a growth in cloud computing. Companies can scaleup by requesting additional resources from cloud services provider ascomputing needs increase and then scale down again as demands decrease.

Cloud computing provides resources as services. “Cloud-computingproviders offer their ‘services’ according to different models, of whichthe three standard models per the National Institute of Standards andTechnology (NIST) are Infrastructure as a Service (IaaS), Platform as aService (PaaS), and Software as a Service (SaaS). These models offerincreasing abstraction; they are thus often portrayed as layers in astack, with infrastructure-as-a-stack serving as the bottom layer;platform-as-a-service serving as the middle layer; andsoftware-as-a-service serving as the top layer. These layers can beimplemented independently of one another. For example, one can provideSaaS implemented on physical machines (bare metal), without usingunderlying PaaS or IaaS layers; and conversely one can run a program onIaaS and access it directly, without wrapping it as SaaS.” (Source:Wikipedia, https://en.wikipedia.org/wiki/Cloud_computing, visited Aug.11, 2016, citations omitted.)

“The NIST's definition of cloud computing defines the service models asfollows:

Software as a Service (SaaS). The capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices througheither a thin client interface, such as a web browser (e.g., web-basedemail), or a program interface. The consumer does not manage or controlthe underlying cloud infrastructure including network, servers,operating systems, storage, or even individual application capabilities,with the possible exception of limited user-specific applicationconfiguration settings.

Platform as a Service (PaaS). The capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages, libraries, services,and tools supported by the provider. The consumer does not manage orcontrol the underlying cloud infrastructure including network, servers,operating systems, or storage, but has control over the deployedapplications and possibly configuration settings for theapplication-hosting environment.

Infrastructure as a Service (IaaS). The capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,and deployed applications; and possibly limited control of selectnetworking components (e.g., host firewalls).” (Source: Wikipedia,https://en.wikipedia.org/wiki/Cloud_computing, visited Aug. 11, 2016,citations omitted.)

One enabling technology for cloud computing is virtualization.“Virtualization software separates a physical computing device into oneor more ‘virtual’ devices, each of which can be easily used and managedto perform computing tasks. Hardware virtualization is thevirtualization of computers as complete hardware platforms, certainlogical abstractions of their componentry, or only the functionalityrequired to run various operating systems. Virtualization hides thephysical characteristics of a computing platform from the users,presenting instead another abstract computing platform,” often referredto as a ‘virtual machine.’ (Source: Wikipedia,https://en.wikipedia.org/wiki/Hardware_virtualization, visited Aug. 11,2016, citations omitted.) The software that controls virtualization isreferred to as a “hypervisor” or “virtual machine monitor.” Theprovisioning and execution of a hypervisor/virtual machine monitor tocreate virtual machines on behalf of the consumer is an example of aservice provided by a public cloud services provider.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a typical virtual machine environment.

FIG. 2 is a block diagram showing a virtual machine environment inaccordance with one embodiment of the invention.

FIG. 3 is a block diagram of a cloud services environment in accordancewith one embodiment of the invention.

FIG. 4 is a diagram showing an apparatus that can be used to implementan embodiment of the invention.

FIG. 5 is a flowchart of a method performed by a consumer of cloudservices in accordance with one embodiment of the invention.

FIG. 6 is a flowchart of a method performed by a cloud services providerin accordance with one embodiment of the invention.

FIG. 7 is a diagram showing components of a consumer domain image inaccordance with one embodiment of the invention.

FIG. 8 is a diagram showing a data physical address in accordance withone embodiment of the invention.

FIG. 9 is a diagram showing virtual to physical memory mapping inaccordance with one embodiment of the invention.

FIG. 10 is a diagram showing another virtual to physical memory mappingin accordance with one embodiment of the invention.

FIG. 11 is a diagram showing initial steps by a cloud services providerto provide a domain image to a consumer in accordance with oneembodiment of the invention.

FIG. 12 is a diagram showing messages between a consumer and a cloudservices provider to provide a domain image to the consumer inaccordance with one embodiment of the invention.

FIG. 13 is a diagram showing a consumer providing an encrypted domainimage in accordance with one embodiment of the invention.

FIG. 14 is a diagram showing messages between components of a cloudservice environment to encrypt a domain image and establish a key domainin accordance with one embodiment of the invention.

FIG. 15 is a diagram showing messages between components of a cloudservice environment to load a consumer's encrypted domain image intomemory of a key domain-capable server in accordance with one embodimentof the invention.

FIG. 16 is a diagram showing the initialization of a key domain inaccordance with one embodiment of the invention.

FIG. 17 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Create Key Domain operation inaccordance with one embodiment of the invention.

FIG. 18 is a diagram showing verification of the domain image inaccordance with one embodiment of the invention.

FIG. 19 is a diagram showing messages between components of a cloudservices environment to verify a domain image in accordance with oneembodiment of the invention.

FIG. 20 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Hash Key Domain operation inaccordance with one embodiment of the invention.

FIG. 21 is a diagram showing switching between key domains in accordancewith one embodiment of the invention.

FIG. 22 is a diagram showing messages between components of a cloudservices environment while executing inside a key domain in accordancewith one embodiment of the invention.

FIG. 23 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Switch Key Domain operation inaccordance with one embodiment of the invention.

FIG. 24 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a walk of paging structures inresponse to a page miss in accordance with one embodiment of theinvention.

FIG. 25 is a diagram showing growth of a domain image in accordance withone embodiment of the invention.

FIG. 26 is a diagram showing messages between components of a cloudbased environment to grow a domain manager (VMMlet) in accordance withone embodiment of the invention.

FIG. 27 is a diagram showing messages between components of a cloudservices provider environment for a running domain manager (VMMlet) torequest more memory pages from a memory manager in accordance with oneembodiment of the invention.

FIG. 28 is a diagram showing messages between components of a cloudservices environment showing requesting additional memory pages whilescheduling VMs on a single CPU in accordance with one embodiment of theinvention.

FIG. 29 is a diagram showing a running domain manager (VMMlet) inaccordance with one embodiment of the invention.

FIG. 30 is a diagram showing multiple virtual machines within a keydomain managed by a domain manager (VMMlet), as well as a second keydomain managed by another domain manager (OSlet) in accordance with oneembodiment of the invention.

FIG. 31A is a diagram showing determination of integrity line locationand slot from a physical memory address in accordance with oneembodiment of the invention.

FIG. 31B is a diagram showing data lines stored in data memory addressspace and integrity values stored in integrity data address space.

FIG. 32 is a diagram showing a system that can be used to implement anembodiment of the invention.

FIG. 33 is a diagram showing a system that can be used to implement anembodiment of the invention.

FIG. 34 is a diagram showing a system that can be used to implement anembodiment of the invention.

FIG. 35 shows an environment in which a non-trusting consumer virtualmachine operates in a protected environment in which actions taken bythe untrusted cloud service provider's virtual machine monitor can beverified.

FIG. 36 shows a data flow for a virtual machine monitor (host VMM) toaccess a virtual machine control structure for a guest virtual machinerunning within a protected key domain.

FIG. 37 shows a process for an agent acting on behalf of a virtualmachine monitor to edit a virtual machine control structure for a guestvirtual machine running within a protected key domain.

FIG. 38 shows an interrupt handler driver for a guest virtual machine toprotect its virtual machine control structure from modification by acompromised virtual machine monitor.

FIG. 39 shows operation of the interrupt handler driver of FIG. 38.

FIG. 40 shows operation of the virtualization exception handler/shim insaving processor register state upon exiting a virtual machine.

FIG. 41 shows creation of a key domain and installation of an encryptedguest code image, along with its encrypted control structure(s), intoencrypted memory.

FIG. 42 shows an alternative process for creating a key domain andinstalling an encrypted guest code image, along with its encryptedcontrol structure(s), into encrypted memory.

FIG. 43 shows one embodiment of a process for the host VMM to verify theconsumer-provided agent VMCS.

FIG. 44 is a data flow diagram showing data flows for a host VMMrequesting an agent to modify Extended Page Tables for another guestVirtual Machine.

FIG. 45 is a flowchart showing loading a virtual machine controlstructure for a guest virtual machine, verifying the virtual machinecontrol structure, launching the guest virtual machine, executing theguest virtual machine code image, and exiting the guest virtual machineto return control to the host virtual machine monitor.

FIG. 46 shows a process for updating a consumer's guest VM image.

FIG. 47 shows a process for adding pages to a consumer's guest VMworkload.

DETAILED DESCRIPTION

In known virtualized environments today, a host Virtual Machine Monitor(VMM)/hypervisor (which shall be referred to as simply a “VMM” or a“host VMM” hereinafter) has full control over the guest virtual machines(VMs) that the host VMM manages. The host VMM can read/write guest VMmemory, modify guest VM control flow (single step, rewind, repeat,debug), read/modify guest VM register state, read/modify guest VMcontrol structures, and so on. However, this complete control over theexecution of the guest VM poses a security risk that the host VMM iscompromised and may modify the guest VM such that consumer's secrets anddata residing within the guest VM are exposed.

In a typical virtualized environment, with a switch from one virtualmachine to another, data structures that pertain to the execution stateof the virtual machine are modified by the VMM. These data structuresmay include a Virtual Machine Control Structure (VMCS) and memorymappings (e.g., Page Tables and Extended Page Tables (EPTs). The VMCS isa data structure in memory that exists once for each logical processorfor each guest VM, while the guest VM is managed by the host VMM. In amulti-processor system, each processor simultaneously executing theguest VM may have a unique VMCS. With every change of the executioncontext between different VMs, the VMCS is restored for thecurrently-executing VM, defining the state of the VM's virtualprocessor. When the execution context switches (VMExits) from a guest VMback to the host VMM, the same VMCS structure is used to restore thehost's processor state from the host state area of the VMCS.

The operating system for a guest VM will form its own memory mappingsbetween virtual and guest physical memory addresses (GPAs) using its ownpage tables. The VMM then uses extended page tables (EPTs) to map guestphysical addresses (GPAs) to the actual physical addresses (PAs) used byhardware to access physical memory. However, these VMM controlled memorymappings can be used by the VMM to compromise a guest VM.

The disclosure presented herein introduces a new model for operation ofthe host VMM where the host VMM operates “blindly,” without the abilityto access data within a guest VM or the ability to access directlycontrol structures that control execution flow of the guest VM. GuestVMs execute within a protected region of memory that even the host VMMcannot access. In one embodiment, the protected region of memory inwhich a guest VM executes is implemented as a key domain, which isencrypted with a consumer-provided key domain key. Key domains aredescribed in detail with respect to FIGS. 1-30 below. In anotherembodiment, the protected region of memory is implemented using rangeregisters, where a designated register blocks the host VMM (and othersoftware) from accessing a guest VM's protected memory region. Forpurposes of this application, the guest VM's protected memory regionwill be described with respect to key domains, although the techniquesdescribed herein are applicable to protected memory regions implementedusing other techniques to make the consumer's guest VM inaccessible tothe host VMM.

Virtualization data structures that pertain to the execution state (e.g.VMCS) and memory mappings of the guest VM are also located in theprotected memory region (key domain). These virtualization datastructures are encrypted with the key domain key. The host VMM and otherguest VMs, which do not possess the key domain key for other keydomains, have no access to modify directly these control structures noraccess the protected memory region.

To enable the host VMM to manage execution of guest VMs without directlymodifying the control structures of the guest VMs, another type of guestVM, referred to herein as a “guest agent VM,” or simply, “agent,” isintroduced. The host VMM launches an agent to operate within theprotected key domain in which the guest VM executes, working with theguest VM to protect the guest VM from tampering. In one embodiment, thevirtualization environment implements policies that enable the agent toaccess and modify the control structures that control execution flow andregister state of other guest VMs on behalf of the host VMM. Bymodifying other guest VM's control structures, the agent can performsuch functions as loading a consumer-supplied image into the guest VMand creating or modifying additional VMCSs and EPTs for multiple guestVMs within a protected memory region (referred to herein as a keydomain). Note that the functionality provided in traditionalvirtualization environments by the host VMM is implemented instead bythe agent upon request by the host VMM, making the agent an intermediaryfor the host VMM.

Furthermore, using the agent as an intermediary between the host VMM andthe guest VM allows the agent to validate that the VMM does notmisconfigure the guest VM to leak confidential data, inject code ordata, or modify the execution flow of the guest VM. In addition, thetechniques disclosed herein enable mutual verification, where the hostVMM can be assured that the guest VM cannot affect host VMM state, whileat the same time the guest VM is assured that the host VMM cannot accessor affect guest VM state.

Thus, in one embodiment, the EPT control structures may also be placedwithin the protected memory of a guest VM, inaccessible by the host VMM.To prevent a guest VM from undermining the security of the host VMM bymaliciously modifying the EPTs, a running guest VM should not be able tomodify its own EPTs. Another trusted VM with another VMCS may be givenaccess to modify the EPTs of another guest VM, but not given the abilityto modify its own EPTs. Alternatively, in an embodiment with a singleguest VM, the guest VM may use its own memory encryption key (key domainkey) to encrypt memory structures on behalf of the host VMM. The guestVM then returns the resulting ciphertext to the host VMM forinstallation into the correct memory locations on the guest VM's behalfunder the host VMM's control.

Using a Hash Key Domain (HashKD) instruction, the host VMM can verifythat the guest-created data structures, such as EPTs, match the hostVMM's expectations and do not allow the guest VM to access the host's orother guest VM's memory space. The HashKD instruction does not revealthe memory contents or secrets of the guest VM, but produces arepresentative SHA hash value that can be used by the host VMM to verifythe memory contents without invoking the guest VM. For example, if theHashKD instruction produces a value that matches an expected hash valuefor the Extended Page Tables (EPTs), the host VMM is assured that thememory was correctly configured by the guest VM and can safely launchthe guest VM.

In one implementation consistent with the present disclosure, Intel®'sVirtualization Technology (VT) and Trusted Execution Technology (TXT)are used in conjunction with a protected memory range inaccessible bythe VMM (but originally accessible to TXT), or memory encryptiontechnology such as Intel®'s Total Memory Encryption (TME), TME withIntegrity (TMEi) or Memory Encryption Engine (MEE). This embodimentremoves the public cloud services provider's Virtual Machine Monitor(VMM)/hypervisor code from the Trusted Code Base (TCB) of the guestvirtual machine (VM)/workload. These techniques protect the consumer'sworkload from access by the host VMM yet enable the host VMM to retainfull control of the platform and manage guest virtual machines runningon the platform.

Memory encryption technology protects guest VM workloads from physicalattacks and prevents the host VMM from accessing the VM's (encrypted)memory. Neither the cloud service provider's software, administrators,nor anyone with physical access to the cloud service provider's serverscan access or modify protected guest VMs.

The present disclosure prevents exposure of consumer data containedwithin a guest virtual machine by protecting the consumer's data fromaccess by the cloud services provider, by the host VMM, by other guestVMs, by administrators or others with physical access, by governments,and so on. The protection provided using the techniques described hereineffectively provides the same level of confidentiality and security asthe consumer would have running the same workload in a private cloud (onpremise). A mutual trust relationship is established between theconsumer and the public cloud services provider by enabling the consumerto verify that the public cloud services provider's processes running inthe cloud have not compromised the consumer's code and data. Similarly,the public cloud services provider is able to verify that the consumer'sprocesses running in the cloud have not compromised the public cloudservices provider's code and data.

Referring now to FIG. 1, a block diagram showing components of a typicalvirtual machine environment 100 is shown. A typical implementation of avirtual machine environment provided in a server of a cloud servicesprovider is shown. Running on the server hardware 110 is a VirtualMachine Monitor (VMM) layer 120. In the typical virtual machineenvironment 100 shown, the VMM layer 120 is computer software orfirmware that creates and runs virtual machines (VMs), such as VM1 130₁, VM2 130 ₂, and VM3 130 ₃, on the cloud services provider's serverhardware 110. Each of VMs VM1 130 ₁, VM2 130 ₂, and VM3 130 ₃ is shownas standalone block in FIG. 1, representing different VMs all under thecontrol of a common VMM layer 120. The VMM layer 120 provides access toserver resources, such as server hardware 110, to the VMs that the VMMcontrols.

The VMM layer 120 uses data structures such as a VM control structure(VMCS) 124 and extended page tables (EPTs) 126 to control execution ofVMs. The VMCS is a data structure in memory that exists once for eachVM, while it is managed by the VMM. With every change of the executioncontext between different VMs, the VMCS is restored for the current VM,defining the state of the VM's virtual processor. Extended page tables(EPTs) are used to launch a VM's virtual processor with privileges as an“unrestricted guest.”

The VMM layer's 120 software or firmware is provided by the cloudservices provider and is part of the Trusted Computing Base (TCB) foreach VM. According to Wikipedia, a “trusted computing base (TCB) of acomputer system is the set of all hardware, firmware, and/or softwarecomponents that are critical to its security, in the sense that bugs orvulnerabilities occurring inside the TCB might jeopardize the securityproperties of the entire system. By contrast, parts of a computer systemoutside the TCB must not be able to misbehave in a way that would leakany more privileges than are granted to them . . . . Modern operatingsystems strive to reduce the size of the TCB so that an exhaustiveexamination of its code base (by means of manual or computer-assistedsoftware audit or program verification) becomes feasible.” (SeeWikipedia, https://en.wikipedia.org/wiki/Trusted_computing_base, visitedAug. 9, 2016.)

In the normal virtual machine environment 100 of FIG. 1, the VMM 122provided by the cloud services provider is in the TCB of each of VMs VM1130 ₁, VM2 130 ₂ and VM3 130 ₃. The inclusion of the VMM 122 in the TCBforecloses a particular VM such as VM1 130 ₁ from seeing, measuring, ortrusting the VMM 122 that controls that particular VM. The cloudservices provider can change the VMM 122 at any time without the VM VM1130 ₁ owner's knowledge. Furthermore, no cryptographic separation existsbetween VMs. If the VMM has been compromised, a corrupt VM can accessprivate data in a second VM via the compromised VMM that nevertheless istrusted by the second VM.

For a consumer to receive assurance that the VMM controlling theconsumer's processes/VMs is trustworthy, most known techniques usehardware to measure the software/firmware running on the remote machinein the cloud (in this case, the VMM 122) and attest back to the consumerthat the software/firmware that is running on the remote machine in thecloud is a version of the software/firmware that the consumer expects.With the public cloud services provider's VMM being included in theconsumer's TCB, the consumer has no way to independently assess anattestation of trustworthiness made by the public cloud servicesprovider.

FIG. 2 is a block diagram of a virtual machine environment 200 inaccordance with one embodiment of the invention. In this environment,the concepts of a key domain and a domain manager are introduced. A keydomain is a cryptographically separate portion of memory, where accessto data stored in memory locations belonging to the key domain requiresusing an associated key domain key to decrypt the data. A domain managermay use a key domain to cryptographically separate data belonging todifferent owners; in a cloud services environment, a domain manager mayuse a key domain to cryptographically separate data belonging todifferent consumers of cloud services, such as banking services.

For example, in the virtualization environment 200 of FIG. 2, keydomains KD1 250 ₁ and KD2 250 ₂ are used to separate data belonging todifferent virtual machines VM1 230 ₁ and VM2 230 ₂. The data belongingto each of virtual machines VM1 230 ₁ and VM2 230 ₂ may include, forexample, consumer secrets (such as bank account numbers, social securitynumbers, etc.) belonging to each virtual machine VM1 230 ₁ and VM2 230₂. As another example, the data belonging to each of virtual machinesVM1 230 ₁ and VM2 230 ₂ may include computer code (also referred to as acode image or simply an image) that is to be executed to protect eachrespective virtual machine's secrets within the cloud servicesprovider's environment.

The respective domain managers (VMMlets 222 ₁ and 222 ₂) play a rolesimilar to that of a virtual machine monitor (VMM, such as VMM 122 ofFIG. 1) on behalf of their respective host owners VM1 230 ₁ and VM2 230₂. A domain manager (VMMlet) provides VMM functionality within a VM,rather than as a completely separate VMM layer as shown in FIG. 1. Thedomain manager (VMMlet) is privileged code having the ability to create,exit, and resume execution of VMs. These privileges may be referred toas “vmxroot” functionality, and include the ability to perform commandssuch as a Virtual Machine Control Structure (VMCS) save/restore, GeneralPurpose Register (GPR) save/restore, and/or vmexit/vmresume.Furthermore, the domain manager (VMMlet) controls critical resourcessuch as Interrupt Descriptor Tables (IDT), Advanced ProgrammableInterrupt Controller (APIC) instructions, and paging data structuressuch as Page Tables and Extended Page Tables (EPTs). In someembodiments, the domain manager (VMMlet) portion may only consist of thedata structures that control the VM, such as the VMCS, its associateddata structures and the EPTs associated with the VM.

A domain manager (VMMlet) limits access by its host VM to acorresponding cryptographically separate portion of memory called a keydomain. The contents of each physical memory location belonging to a keydomain are hardware-encrypted using a common key domain key. When thehardware writes data to a memory location belonging to a key domain, thedata are encrypted using the key domain key; when the hardware readsdata from a memory location belonging to the key domain, the data aredecrypted using the key domain key.

In one embodiment, the key domain key is created by the consumer owningthe key domain and securely provided directly to the cloud servicesprovider's server hardware. In other embodiments, the consumer maytranslate a key provided by another entity (such as the cloud servicesprovider's server) into another key that is used to encrypt memorylocations belonging to a key domain. In still other embodiments,different keys may be used to encrypt different IP blocks (sets ofmemory locations) belonging to the key domain; for example, a differentkey may be used for encrypting an IP block containing code for anconsumer VM image from the key used to encrypt other consumer secrets.To simplify the descriptions of embodiments herein, the presentapplication describes the contents of each physical memory locationbelonging to a key domain as encrypted by a key domain key that iscreated by the consumer owning the key domain, although otherembodiments are within the scope of the invention.

If contents of the physical memory locations belonging to a key domainare decrypted using the wrong key domain key, the resulting plaintextwill be corrupted. Furthermore, if the memory is integrity protected,and the contents of the physical memory locations belonging to the keydomain are decrypted using the wrong key domain key, the resultingplaintext will not satisfy integrity criteria for the physical memorylocations belonging to the key domain. While the scope of the inventiondoes not require that memory locations belonging to a key domain areintegrity-protected, memory integrity protection may be used to enhancethe security of the techniques described herein.

In one embodiment, a key domain is defined using unused physical addressbits (or other metadata passed through a cache). For example, becausethere will likely be fewer physical memory locations installed in asystem than can be addressed using a 64-bit physical memory address, theunused most significant address bits can be used to select betweendifferent key domains. Two different key domain addresses can alias tothe same physical memory location. However, when data from that physicalmemory location is read into a cache, the cache holds the key domainaddresses independently at the full address resolution (e.g., includingthe full 64-bit physical memory address). The key domain addressuniquely identified when considering the unused physical address bits ofthe full 64-bit physical memory address determines the key domain towhich the physical memory location belongs. By identifying the keydomain to which the physical memory location belongs, the key domain keythat can be used to decrypt the contents of that physical memorylocation is also identified.

A memory manager can select between different address values that aliasto the same physical memory location; i.e., the memory manager canselect between different key domains based upon the address alias. Inone embodiment, integrity check values (ICVs, such as keyed-hash messageauthentication codes (HMACs)), are calculated using a key domain keycreated by the owner of the key domain (the consumer). The memorymanager can access an integrity check value table (or authorized portionthereof) to determine whether the correct key domain key was used toaccess the data. If the wrong key domain key was used to decrypt thedata, the resulting plaintext will be corrupted and will not match acorresponding integrity check value in the integrity check value table.

In one embodiment, when data are read into a cache line, the data arecompressed to provide space for integrity check values and/or the keydomain identifier/selector (i.e., the unused address bits are embeddedinto the cache line). The key domain identifier/selector may also beincluded in the compressed data when writing to memory. When readingmemory for a compressed data line, the actual unused address bitsdesignating the key domain are compared with the key domainidentifier/selector value that was embedded in the compressed datacache. If the key domain values match, the data are decompressed andforwarded to the cache. Compression is an integrity optimization toavoid the need to consult an integrity check value table each time thatdata is accessed in memory. Furthermore, compression of the key domaininto the cache line alleviates the need for some caches to include a keydomain identifier as metadata. While some embodiments of the inventionmay compress data written to a cache line or memory, compression of thedata is not required to implement the present invention.

If the key domain values do not match when the actual unused addressbits designating the key domain are compared with the key domainidentifier/selector value that was embedded in the compressed datacache, a determination is made of which key domain is currentlyauthorized. If the address used to read memory corresponds to thecurrent key domain, the data are cleared (i.e., data bits are set tozeroes) and a cache eviction of the old key domain address is performed.(Although both key domain addresses alias to the same physical memorylocation, the cache holds the key domain addresses independently at thefull address resolution.)

Referring again to FIG. 2, each of VM1 230 ₁ and VM2 230 ₂ is shown withits own domain manager (VMMlet) 222 ₁ and 222 ₂. Domain manager VMMlet1222 ₁ is shown inside VM1 230 ₁, and domain manager VMMlet2 222 ₂ isshown inside VM2 230 ₂, to represent that code for each respectivedomain manager (VMMlet) is included within code for the respective VM.When a consumer requests services requiring virtualization, a code imageimplementing functionality of a domain manager (VMMlet) is provided bythe cloud services provider to the consumer. The domain manager (VMMlet)image provided by the cloud services provider is incorporated into theconsumer's domain (VM) image.

A consumer owning VM1 230 ₁ can measure and verify the domain manager(VMMlet) 222 ₁ code before incorporating VMMlet1 222 ₁ into theconsumer's domain (VM1 230 ₁) image. By placing the consumer's VM incontrol of the entire software stack of the consumer's VM image,including the domain manager (VMMlet), the consumer can measure, verify,and trust the image that is used to instantiate the domain manager(VMMlet) running within the consumer's VM. Finally, the consumer createsa domain launch image (including the domain manager image) that ismemory position-dependent based on physical addresses, encrypts thedomain launch image with the consumer's own key domain key, and providesthe encrypted domain launch image to the cloud services provider serverthat will launch that domain launch image.

In one embodiment, the consumer creates an encrypted domain launch imagein an attested SGX (Intel® Software Guard Extensions) enclave on thecloud services provider's server. In this embodiment, the domain launchimage is encrypted with the key domain key inside the enclave and theencrypted domain launch image (and any associated ICV values) is writtento memory outside the enclave.

When the cloud services provider receives the encrypted domain launchimage (including the domain manager image) from the consumer, the cloudservices provider can measure, verify, and trust that theconsumer-encrypted domain launch image contains the same domain managerimage that was provided to the consumer. In one embodiment, the cloudservices provider's server hardware provides a mechanism to measure(create a hash of) the domain manager portion of the consumer-encrypteddomain launch image, so the cloud services provider can then attest thatthe domain manager image included in the consumer-encrypted domainlaunch image is the same as the domain manager image that the cloudservices provider supplied (and is therefore is trusted by the cloudservices provider). In one embodiment, the hash function measuring thedomain manager image is position-dependent, so that the domain managerimage must be loaded into the correct memory location of the cloudservices provider server's memory to be decrypted properly. For example,even if the contents of two different memory locations are the same (forexample, all zeroes), only the domain manager image loaded into thecorrect memory location will produce the expected position-dependenthash result. The property of a position-dependent hash verificationfunction provides a security advantage that encrypted portions of thedomain manager image cannot be rearranged in memory by an adversary inan attempt to alter the behavior of the domain manager image.

In this cooperative model, the domain manager image is verified by boththe consumer and the cloud services provider. The consumer can trust adomain manager image provided by the public cloud services provider, andtrust that the hardware of the cloud services provider will enforcesecurity and confidentiality for consumer virtual machines (VMs). Thisverification is important to the security of the VM because the domainmanager (VMMlet) has full vmxroot privileges, including the ability toperform commands such as a Virtual Machine Control Structure (VMCS)save/restore, General Purpose Register (GPR) save/restore, and/orvmexit/vmresume. Furthermore, Interrupt Descriptor Tables (IDT),Advanced Programmable Interrupt Controller (APIC) instructions, andpaging data structures (such as Page Tables and/or Extended Page Tables(EPTs)) are encrypted in the key domain. In some embodiments, the domainmanager image only consists of the VM control structures such as theVMCS and associated data such as the EPTs that control the behavior ofthe consumer's VM, but not the code or data used for VMX root operationwhich can reside outside of the consumer's key domain.

This cooperative model enables a consumer to trust privileged softwareprovided by the cloud services provider by moving measurement andverification to the consumer. The consumer can assure the security ofthe consumer's own workload in the cloud, guaranteed by the cloudservices provider's server hardware. The cloud services provider canthen re-verify that the correct domain manager image was used. Thismodel greatly simplifies the hardware requirements for providing a truesecure public cloud foundation. No changes are needed to the operatingsystem (OS) portion of a virtual machine (VM). Most of the complexity ofimplementation is contained in the design of the domain manager(VMMlet), which is software that can easily be patched, updated,measured, and certified. In one implementation, hardware instructionsare used for creating a key domain, switching between key domains, andverifying the contents of a key domain by computing a hash value of thecontents of the memory locations corresponding to the key domain andcomparing the hash value to an expected hash value for valid contents ofthe key domain.

Referring again to FIG. 2, a processor (included in hardware 210)switches between VMs 230 ₁ and 230 ₂ and their respective key domainsKD1 250 ₁ and KD2 250 ₂ using a SwitchKD (switch key domain) instructionin response to a command issued by memory manager 240. The result ofswitching from one key domain to another (e.g., from key domain KD2 250₂ to KD1 250 ₁) is that control over a particular physical memory aliasis passed to a VM (230 ₁) that is authorized to access the current keydomain KD1 250 ₁. Different hardware key domains accessed via key domainkeys prevent information leaks of consumer private data across VMs andeven by an adversary with access to the external physical memory manager240. A key domain identifier/selector (e.g., part of the physicaladdress) keeps VM memory regions separate in cache. In one embodiment,instead of a switch key domain instruction, the VMX rootvmlaunch/vmresume instructions will switch the key domain to the keydomain containing the VMCS as identified by the key domain identifier inthe address provided by the vmptrld instruction, which loads the pointerto the current VMCS from the address specified in the vmptrldinstruction. A vmexit will then switch back to the VMX root key domainor shared memory region.

In one embodiment, a portion 212 s of memory 212 is shared and is usedto communicate across key domain cryptographic boundaries. In otherwords, the shared memory is not encrypted and can be used to communicatemessages between VMs that otherwise can only access memory locationsbelonging to the key domain for which each particular VM is authorized.The shared memory is shown as having a physical address with a bit,described herein as a “k-bit,” disabled. The k-bit is used to determinewhether the current key domain is used to limit VM access to memorylocations belonging to a key domain (such as one of key domains KD1 250₁ or KD2 250 ₂), or allow sharing unencrypted information across keydomains in shared memory 212 s. The k-bit indicates to the CPU whetherthe key domain indicated in a physical address should be set to theshared key domain (plaintext/!k) or to the currently active key domain(encrypted).

The above embodiment has been described with regard to a domain manager(VMMlet) that manages virtual machines, although the invention is not solimited. A similar key domain model can be used to support processes orcontainers; although there is no corresponding VMM, the OS kernel (ormicrokernel) serves a similar purpose. Each process or container imagein each key domain will have cooperating OS kernel components (referredto herein as a domain manager or OSlet) that are measured by the cloudservices provider. A domain manager (OSlet) responds to memory managercommands, interrupts, scheduling, resource management, etc., in asimilar manner as the domain manager (VMMlet).

Referring now to FIG. 3, shown is a block diagram of a cloud servicesenvironment in accordance with an embodiment of the present invention.As shown in FIG. 3, network 300 can be used to allow consumers torequest services, including virtualization services, from a public cloudservices provider. As seen, network 300 can correspond to any type ofcommunications network and can include many different types of computingdevices interconnected via a given network such as Internet 320.

Cloud storage 310 can be provided as part of a data center that includesvarious computing devices, storage devices and so forth. As one example,cloud storage 310 can be a storage device that includes multiple storagecomponents such as disks, optical, or semiconductor-based storage. Cloudstorage 310 can act, for example, as a repository of master copies ofvarious applications, including a virtual machine monitor (VMM)application that instantiates virtual machines to provide services inresponse to a consumer's request. In the embodiment shown in FIG. 1, amaster copy of a VMM application is stored in the form of VMM image 312.VMM image 312 is a software image containing a software stack designedto provide a virtual machine platform in the form of a virtual machinemonitor (VMM).

Thus as further seen in FIG. 3, at the same location, e.g., as part ofthe same data center, one or more public cloud services providerservers, such as public cloud provider servers 315 ₁ and 315 ₂ can becoupled to cloud storage 310. In various embodiments, public cloudservices provider servers can be used to service consumer servicesrequests, including virtualization requests. For example, each publiccloud services provider server may host one or more virtual machines onbehalf of a consumer. In the example shown in FIG. 3, public cloudprovider server 315 ₁ hosts two virtual machines, VM1 340 ₁ and VM2 340₂. Similarly, public cloud provider server 315 ₂ hosts two virtualmachines, VM1 340 ₃ and VM2 340 ₄.

As shown in FIG. 3, various consumer devices can be present, e.g., cloudservices consumer devices 330 ₁ and 330 ₂. Such cloud services consumerdevices may be personal devices of a given user such as a smartphone,tablet computer, desktop computer or so forth. Alternatively, cloudservices consumer devices may be servers for an organization thatconsumes cloud services. In addition, cloud services consumer devicesmay be emulated via software. In other words, an emulator or simulatorcan emulate the cloud provider's hardware in software such that theconsumer may run emulators of the cloud provider's hardware on theconsumer's devices.

Each of cloud services consumer devices 330 ₁ and 330 ₂ provides arespective cloud services consumer 331 ₁ and 331 ₂ and a respective VMimage 332 ₁ and 332 ₂. Cloud services consumers 331 ₁ and 331 ₂ may be,for example, a client component of a cloud services application used torequest cloud services. Cloud services consumers such as cloud servicesconsumers 331 ₁ and 331 ₂ are referenced herein as “consumers.” VMimages 332 ₁ and 332 ₂ may be stored in storage (not shown) coupled tothe respective cloud services consumer devices 330 ₁ and 330 ₂. These VMimages are provided by the consumer to the cloud services provider andused to create a secure VM, such as VM1 340 ₁, running on the cloudprovider's server 315 ₁.

When a secure VM has been established on the cloud services provider'sserver in accordance with the techniques described herein, the consumermay then use that VM, with the consumer's secret keys, to createadditional VMs on behalf of the consumer. Thus, once one consumer VM canbe securely established in the cloud services provider's cloud, that VMcan then perform all the operations of the consumer devices in FIG. 3,including creating additional secure VMs.

Likewise, a consumer can establish secure VMs with multiple cloudservices providers and these secure VMs can interact securely via securecommunications channels using the consumer's secret keys.

FIG. 4 is a diagram showing an apparatus in accordance with oneembodiment of the invention. An apparatus 400 to secure a public cloudenvironment according to an embodiment is shown. The apparatus 400 mayinclude any computing device and/or data platform such as a laptop,personal digital assistant (PDA), media content player, imaging device,mobile Internet device (MID), any smart device such as a wireless smartphone, smart tablet, smart TV, computer server, and so on, orcombinations thereof. In addition, the apparatus 10 may include anyplatform having computing functionality (e.g., personal digitalassistant/PDA, laptop, smart tablet), communications functionality(e.g., wireless smart phone), imaging functionality, media playingfunctionality (e.g., smart television/TV), and so on, or combinationsthereof (e.g., mobile Internet device/MID).

The illustrated apparatus 400 includes memory 412. The memory 412 may beexternal to a processor 411 (e.g., external memory), and/or may becoupled to the processor 411 by, for example, a memory bus. In addition,the memory 412 may be implemented as main memory. The memory 412 mayinclude, for example, volatile memory, non-volatile memory, and so on,or combinations thereof. For example, the memory 412 may include dynamicrandom access memory (DRAM) configured as one or more memory modulessuch as, for example, dual inline memory modules (DIMMs), small outlineDIMMs (SODIMMs), etc., read-only memory (ROM) (e.g., programmableread-only memory (PROM), erasable PROM (EPROM), electrically EPROM(EEPROM), etc.), phase change memory (PCM), and so on, or combinationsthereof.

The memory 412 may include an array of memory cells arranged in rows andcolumns, partitioned into independently addressable storage locations.Thus, access to the memory 412 may involve using an address for astorage location such as, for example, a row address identifying the rowcontaining the storage memory location and a column address identifyingthe column containing the storage memory location. In addition, a deviceinternal to the apparatus 400 and/or a device external to the apparatus400 may accomplish access to the memory 412. Access to the memory 412may involve, for example, direct memory access (DMA).

Memory 412 may be protected using encryption and integrity checking. Inone embodiment, an encryption technique called a tweakable block cipheris used. A tweakable block cipher accepts a second input, called atweak, along with plaintext or ciphertext input to be encrypted. Thetweak, along with the key, selects the permutation computed by thecipher. For example, a tweak function may use a physical memory addressas a tweak to a block cipher to bind unencrypted data with the physicalmemory address. The tweak function 445 may include, for example, XTS(XOR-encrypt-XOR)/XEX-based tweaked codebook mode with ciphertextstealing) algorithm, Liskov, Rivest, and Wagner (LRW) algorithm, and soon, or combinations thereof.

With regard to integrity of memory 412, in one embodiment, a hardwarecapability based on memory encryption with integrity is used, which isdescribed in U.S. Pat. No. 9,213,653 B2, “Memory Integrity,” hereinafterreferred to as a Total Memory Encryption engine with integrity, or TMEi.In another embodiment, memory encryption with integrity is provided by aMemory Encryption Engine (MEE), as described in U.S. Pat. No. 8,819,455,“Parallelized Counter Tree Walk for Low Overhead Memory ReplayProtection.” The present invention is not limited to theseimplementations, however, as any cryptographic mechanism providingmemory encryption via a memory position-dependent (“tweaked”) cipher canbe used. Furthermore, any memory integrity mechanism can be used toenhance the security provided by encryption alone, although a memoryintegrity mechanism is not required for implementation of the invention.

The processor 411 may include any type of processor such as, forexample, micro-processor, an embedded processor, a digital signalprocessor (DSP), a central processing unit (CPU), a graphical processingunit (GPU), a visual processing unit (VPU), a network processor, adevice to execute code to implement the technologies described herein,and so on, or combinations thereof. The processor 411 may include one ormore cores such as, for example, a core 416 and a core 418. The cores416, 418 may include a single-threaded core, a multithreaded coreincluding more than one hardware thread context (or “logical processor”)per core, and so on, or combinations thereof. The cores 416, 418 mayinclude an instruction decoder to recognize and/or decode an instruction(e.g., from an instruction register), to activate appropriate circuitryto execute the instruction, to verify that a stream of instructions(e.g., operation codes, etc.) will compute, and so on, or combinationsthereof.

For example, the cores 416, 418 may execute one or more instructionssuch as a read instruction, a write instruction, an erase instruction, amove instruction, an arithmetic instruction, a control instruction, andso on, or combinations thereof. The cores 416, 418 may, for example,execute one or more instructions to move data (e.g., program data,operation code, operand, etc.) between a register (not shown) and thememory 412, to read the data from the memory 412, to write the data tothe memory 412, to perform an arithmetic operation using the data (e.g.,add, subtract, bitwise operation, compare, etc.), to perform a controloperation associated with the data (e.g., branch, etc.), and so on, orcombinations thereof. The instructions may include any coderepresentation such as, for example, binary code, octal code, and/orhexadecimal code (e.g., machine language), symbolic code (e.g., assemblylanguage), decimal code, alphanumeric code, higher-level programminglanguage code, and so on, or combinations thereof. Thus, for example,hexadecimal code may be used to represent an operation code (e.g.,opcode) of an x86 instruction set including a byte value “00” for an addoperation, a byte value “8B” for a move operation, a byte value “FF” foran increment/decrement operation, and so on.

The processor 411 may include internal storage such as, for example, aprocessor cache including one or more levels. The processor cache maynot be encrypted and/or may share a same die as the processor 411, onthe same chip. In addition, the processor cache may be integrated ontoone or more of the cores 416, 418. The illustrated processor 411includes a cache 413, which may store data (e.g., instructions,operands, program data, etc.) utilized by one or more components of theprocessor 411. The cache 413 may include any type of cache such as, forexample, an instruction cache, a data cache, a single level cache, amultilevel cache, a shared cache, a strictly inclusive cache, anexclusive cache, and so on, or combinations thereof. For example, thecache 413 may include a mid-level cache, such as level 2 (L2), level 3(L3), level 4 (L4), or other levels of cache, a last level cache (LLC),and so on, or combinations thereof. The cores 416, 418 may check whetherdata is located in the cache 413 to execute one or more instructionsand/or other data (e.g., program data, etc.), wherein a cache miss maycause a transfer of the data from the memory 412 to the cache 413 in ablock of fixed size (e.g., cache line).

Each core 416, 418 may be, for example, coupled with respective memoryvia a respective memory controller such as memory controller 417,coupled with shared memory via a shared memory controller, coupled withrespective memory via a shared memory controller, and so on, orcombinations thereof. In addition, a shared cache may be coupled with ashared memory controller, a plurality of caches may be coupled with aplurality of respective memory controllers, and so on, and combinationsthereof. For example, the memory controller 417 may be shared among thecores 416, 418, may be coupled with the cache 413 (e.g., sharedmultilevel cache), and may couple the cores 416, 418 with the memory 412(e.g., shared DRAM). The memory controller 417 may be coupled with thememory 412 (e.g., external memory, DRAM, etc.).

Processor 411 also includes memory encryption engine 415. Theillustrated memory encryption engine 415 includes an encryptor 441,which may encrypt unencrypted data. The unencrypted data may include,for example, cleartext data, plaintext data, and so on, or combinationsthereof. The cleartext data may be subject to encoding in a specialformat (e.g., hypertext transfer markup language (HTML), rich textformat (RTF), etc.) and read by an appropriate program (e.g., wordprocessor, text editor, etc.) without the need for decryption. Theplaintext data may include pre-encryption data such as, for example,cleartext data which is to be encrypted prior to transmission and/orstorage. In addition, the plaintext data may include post-decryptiondata such as, for example, data which is the result of decryption onreceived and/or retrieved data.

Additionally, the plaintext data may include data which is encodable inany format, such as audio/video data (e.g., moving picture experts group(MPEG) data, etc.), image data (e.g., joint photographic experts group(JPEG) data, etc.), financial data (e.g., automatic transfer machine(ATM) transaction data, etc.) and so on, or combinations thereof. Theplaintext data may include program data such as, for example, at least apart of a program, an operating system (OS), an application, a virtualmachine (e.g., Virtual Machine Monitor (VMM) code, etc.), and so on, orcombinations thereof. The plaintext data may also include, for example,an instruction including an opcode, an operand, and so on, orcombinations thereof.

The unencrypted data may include a plurality of bits. The plurality ofbits may include one or more bits (e.g., a byte, etc.) in any coderepresentation, such as binary code, octal code, hexadecimal code,symbolic code, decimal code, alphanumeric code, higher-level programminglanguage code, and so on, or combinations thereof. For example, a memoryreference instruction may include a bit for an opcode, a bit for anaddress, and so on, wherein the bits of the memory reference instructionmay be represented in hexadecimal code (e.g. machine language), insymbolic code (e.g., assembly language), and so on, or combinationsthereof. Additionally, the plurality of bits may be translated to and/orfrom binary code, wherein the binary code may be executed by the cores416, 418, may be sorted at the memory 412, may be fetched from thememory 412, and so on, or combinations thereof.

The encryptor 441 may include any type of cipher to generate cyphertextdata such as, for example, a block cipher in any desired mode ofoperation. The block cipher may include a fixed block size, wherein theblock cipher may be repeatedly implemented to encrypt data larger thanthe block size. For example, the block cipher may include AdvancedEncryption Standard (AES) in a propagating cipher-block chaining (PCBC)mode of operation. In addition, the block cipher may include anexpandable block size.

In one example, the block cipher is Threefish, which may be implementedto obtain an expandable block size of any length (e.g., 256 bits, 512bits, 1024 bits, etc.). For example, Threefish may utilize a tweak(e.g., 128 bits), which may include a memory address and/or location,and a key which may be the same width as the block. Threefish mayutilize a number of rounds (e.g., 72) to encrypt for blocks of 256 bitsand 1024 bits, a number of rounds (e.g., 80) for blocks of 1024 bits,and so on. Threefish may utilize a function MIX including an additionoperation, a rotation operation by a constant, and an exclusive-or (XOR)operation. Words may be permutated, for example, after each set of MIXfunctions (e.g., 2, 4, or 8, respectively by block size). A subkey maybe injected into the system, for example, every number of rounds (e.g.,4) wherein the subkey may be generated by parts of the key, the tweak,and a counter value. The key and the tweak may be given an extra word atthe end (e.g., an XOR of all the other words).

The illustrated memory encryption engine 415 also includes a decryptor442, which may decrypt ciphertext data to generate unencrypted data. Thedecryptor 442 may include an inverse of the encryptor 441. For examplethe decryptor 442 may include an inverse of AES-PCBC. In addition, thedecryptor 442 may include an inverse of Threefish. For example, thesubkeys may be applied in reverse order, with each round including thereverse word permutation followed by the reverse MIX functions. Thus,unencrypted data (e.g., plaintext data) may be implemented as input tothe encryptor 441 to generate an unreadable copy of the unencrypted data(e.g., ciphertext data) when the unencrypted data is to be stored in thememory 412 (e.g., write instruction), wherein the decryptor 442 may beimplemented to decrypt the ciphertext data and generate the unencrypteddata when the ciphertext data is to be fetched from the memory 412(e.g., read instruction).

The memory encryption engine 415 may include a cache line monitor toidentify a cache line corresponding to a freed address alias frommultiple address aliases, and flush the identified cache line. Thememory encryption engine 415 may also include an integrity check valueselector 443 to determine integrity check values to apply to unencryptedand/or encrypted data lines (e.g., aliased by at least one of aplurality of address aliases). The memory encryption engine 415 may alsoinclude a memory initializer to write to a location in the memorywithout first reading previously stored data at the location in thememory. The memory encryption engine 415 may include an allocator toassign/bind a flushed cache line to a data line physical address.

The memory encryption engine 415 may further include a cache lineinterpreter to determine, for each cache line, a data physical memoryaddress, as illustrated in FIG. 31A, that includes: data line bytes; adata line physical address comprising an integrity line slot selectorand an integrity line index; and a key domain selector formed fromunused address bits of the data physical memory address. The integrityline index identifies an integrity line address location in the memory,and the integrity line slot selector identifies an integrity line slotin the integrity line address where an integrity line slot value isstored and used to determine whether an address alias is valid.

The memory encryption engine 415 may further include an alias manager todetermine the data line physical address for multiple cache lines thatidentify alias addresses, wherein the alias addresses alias to a singlememory location. The memory encryption engine 415 may include anintegrity check value calculator to set the key domain selector of acache line with a valid integrity value to designate the cache line as acurrently valid address alias. The memory encryption engine 415 mayinclude a data retriever to read the encrypted data line from the dataline physical address of the data physical memory address for the cacheline, and a decryptor 428 to decrypt the encrypted data line. Adecrypted data line may identify the data line physical address, theintegrity line index and the integrity line slot selector for thedecrypted data line (e.g., as illustrated in FIG. 31A). The memoryencryption engine 415 may include a slot value interpreter to read anintegrity line slot value stored in the integrity line slot and acomparator (e.g., integrity verifier 444) to confirm a match between theintegrity line slot value and the key domain selector of the dataphysical memory address for the decrypted data (e.g., data line).Integrity verifier 444 may determine a mismatch/match between plaintextof an integrity value (e.g., a copy stored in an integrity check line)and plaintext of a data line (e.g., a portion copied of the data line),which indicates error corruption or validity of the integrity valueand/or of the data line. Integrity verifier 444 may further compare ahash value of data to an expected hash value for the data.

The memory encryption engine 415 and/or alias manager may store aliasbits (e.g., the integrity line slot selector, the integrity line index,a key domain selector, and/or valid integrity value, or some combinationthereof), separate from the data line bytes, in a separate location(e.g., an alias bits cache line and/or alias bits memory location),which the memory encryption engine 415, a data retriever and/or aliasmanager may retrieve and compare with a request (e.g., request for dataidentified by a corresponding data line physical address) to ensure thata particular access control policy matches. In the event the alias bitscompare with the request fails (e.g., no match results), the memoryencryption engine 415 and/or alias manager may report (e.g., raise analert) the no match condition as one or more of an error or a fault.

The memory encryption engine 415 data retriever (or cores 416, 418) mayread the encrypted data line from the data line physical address of thedata physical memory address for the at least one cache line of theplurality of cache lines. The decryptor 442 may decrypt the encrypteddata line, wherein the decrypted data line identifies the data linephysical address, the integrity line index and the integrity line slotselector for the decrypted data line. The comparator (e.g., integrityverifier 444) may identify no match between the integrity line slotvalue stored and the key domain selector of the data physical memoryaddress for the decrypted data line, and the memory encryption engine415 and/or comparator, responsive to the no match identification, maycause the memory encryption engine 415 or a component thereof to flushthe cache line, and report the no match condition as one or more of anerror or a fault.

The memory encryption engine 415 may further include an integrity valueembedder to embed, for each cache line, the data line bytes with thevalid integrity value for the data physical memory address. The memoryencryption engine 415 may also include a compressor to compress the dataline bytes embedded with the valid integrity value. The encryptor 441may encrypt the compressed data line bytes embedded with the validintegrity value. The memory encryption engine 415 may further include adata line writer to write to the location in the memory identified, bythe data line physical address, the valid integrity value to the keydomain selector, the data line physical address, and the encrypted andcompressed data line bytes embedded with the valid integrity value.

The memory encryption engine 415 and/or the compressor may determine thedata line bytes of a particular cache line to be uncompressible, andinstead of attempting to embed alias bits (e.g., the integrity line slotselector, the integrity line index, a key domain selector, and/or validintegrity value, or some combination thereof) into the data line withthe data line bytes, may store the valid integrity value separately(e.g., in a separate location such as a another cache line and/or memorylocation).

The illustrated ciphertext discussed herein may be decrypted to generateunencrypted data when the ciphertext is to be fetched from the memory412 (e.g., read operation). The illustrated memory encryption engine 415may further include a tweak function 445 to utilize a physical memoryaddress as a tweak to a block cipher to bind unencrypted data with thephysical memory address. The tweak function 445 may include, forexample, XTS (XOR-encrypt-XOR)/XEX-based tweaked codebook mode withciphertext stealing) algorithm, Liskov, Rivest, and Wagner (LRW)algorithm, and so on, or combinations thereof. The tweak function 445may, for example, spread the original physical memory address, XOR theaddress with the unencrypted data, and run the result through theencryptor 441 with a key to bind the unencrypted data to the address.

The illustrated memory encryption engine 415 may further include adecoder 447 to decode the unencrypted data and recognize one or moreinstructions. For example, uncorrupted unencrypted data (e.g., validplaintext) may contain opcodes when substantially an entire data line(e.g., a 64-byte cache line) is fetched from the memory 102 and isdecrypted. Thus, the decoder 447 may recognize an opcode of aninstruction set such as, for example, an x86 instruction set, etc., whenthe decoder 447 decodes the plaintext data.

The illustrated memory encryption engine 415 may further include akey/tweak value selector 448 to select a key from a plurality of keys(e.g., a key domain) and/or a tweak from a plurality of tweaks (e.g., atweak domain) for a physical location in the memory 412. For example,the illustrated memory encryption engine 415 may include a functiondetector to determine that a function (e.g., a program, middleware, anoperating system, firmware, virtual machine, VMM, Operating System (OS)kernel, etc.) or a part of the function (e.g., part of a program, etc.)is being launched for the first time, or is being given access to aphysical location in the memory 412 for the first time. The key/tweakvalue selector 448 may, in response, select a key and/or a tweak (e.g.,a key from a key domain, a different key from a same key domain, adifferent key from a different key domain, a tweak from a tweak domain,a different tweak from a same tweak domain, a different tweak from adifferent tweak domain, etc.) for the physical location in the memorywhen the function (and/or part thereof) is given access.

The key/tweak value selector 448 may select a key based on a valuedetermined from a bit of a physical memory address for a data line, suchas an unused address bit. A key domain for a specific physical memorylocation may be defined by a number of unused address bits to beselected to determine the value. For example, a particular physicalmemory location may belong to a particular key domain at one time,wherein the unused address bits may be used to define the key domain(e.g., a key domain including 16 keys for a single physical memorylocation where four unused address bits are utilized). Thus, thephysical memory location may use different keys at different points intime based on a domain to which the location maps. The key/tweak valueselector 448 may derive the key by, for example, encrypting the value(e.g., 0001, 0010, etc.) using a secret master key that may be protected(e.g., in a trusted execution environment) by the apparatus 400. Inaddition, the key/tweak value selector 448 may derive the key by, forexample, retrieving the key from an array of protected keys using thevalue as a pointer to the array.

Moreover, the key/tweak value selector 448 may select a tweak by settinga bit of the physical memory address that is to be used as a tweak bythe tweak function 445. In this regard, a tweak for XTS mode willinclude the unused address bits and the used address bits of a physicalmemory address. Thus, different ciphertext will result from differentaddresses used for the tweak (even if actually referring to the samephysical memory location) when the unused address bits areselected/changed by the key/tweak value selector 448.

The illustrated memory encryption engine 415 also includes logic 449,which may utilize components of the processor 410 such as, for example,the cores 416, 418, the encryptor 441, the decryptor 442, etc., tomaintain (e.g., ensure, verify, test, etc.) the security and integrityof the memory 412.

Memory corruptions caused from components (e.g., internal or externaldevices, accelerators, etc.) may be detected as these components accessmemory with addresses that may pertain to a particular key domain oralias and tweak. These devices may use the current and correct addressfor accessing memory. Similarly, and inversely, software corrupting thememory of such devices may also be detected when an incorrect ornon-current address is used.

Although not illustrated in FIG. 4, the apparatus 400 may include otherelements on chip with the processor 411. For example, the processor 411may include input output (IO) control logic integrated with the memoryencryption engine 415. In addition, the apparatus 400 may include, forexample, an IO module, sometimes referred to as a Southbridge of achipset, that functions as a host device and may communicate with, forexample, a front/rear image sensor (e.g., a two-dimensional camera, athree-dimensional camera, etc.), a microphone, a display (e.g., screen),a motion sensor (e.g., an accelerometer, a gyroscope, etc.), massstorage (e.g., hard disk drive/HDD, optical disk, flash memory, etc.), anetwork interface to provide a wide variety of communicationfunctionality (e.g., cellular telephone, WiFi, WiMax Global PositioningSystems (GPS), spread spectrum (e.g., 900 MHz), other radio frequency(RF), etc.). The processor 14 and the IO module may, for example, beimplemented as a system on chip (SoC).

Additionally, while examples have shown separate components forillustration purposes, it is should be understood that one or more ofthe components of the apparatus 400 may be combined, may reside in thesame and/or different physical and/or virtual locations, and so on, orcombinations thereof. For example, the logic 449 may include one or moreof the components of the memory encryption engine 415 to executecorresponding functionality thereof, which may reside in the same ordifferent location as the cores 416, 418, the memory 412, and so on, orcombinations thereof. In addition, one or more components of the memoryencryption engine 415 may be implemented in computer program code, suchas a software value selector that may interface with one or morecomponents of the memory encryption engine 415 implemented in logichardware.

Some of the functionality provided by apparatus 400 may be delivered bya System-on-Chip (SoC) IP block on the memory/DRAM (dynamic randomaccess memory) side of the processor cache, enabling the functionalityto be used for software running on the host processor (e.g., centralprocessing unit/CPU) cores, as well as on other IP blocks andaccelerators such as General Purpose Graphics processing unit (GPGPUs)and integrated graphics (e.g., Intel® Processor Graphics).

The illustrated apparatus 400 employs unused physical address bits(and/or other metadata passed through the cache) to manipulatecryptographic memory integrity values pointers (e.g., implementing oneor more access control policies), enabling software memory allocationroutines to control assignment of pointers (e.g., “malloc” and “free”).The apparatus 400 may generally use unused address bits as a key domain.For example, there may be less external physical memory installed in asystem than can actually be addressed by a 64 bit physical memoryaddress, so the most significant address bits may be used to selectbetween different “key domains”, as the caches may still convey theseaddresses at the physical memory addresses full resolution to theapparatus 400. The illustrated apparatus 400 may use 5-level paging forvirtual memory and 64-bit addressing to allow a software memoryallocator/manager (e.g., memory manager 240 of FIG. 2) to select betweendifferent address values that alias to the same physical memorylocation. The software memory allocator/manager may control an integrityvalue table (or authorized portion thereof) to determine which alias iscurrently valid, so that use of invalid aliases/addresses by softwaremay then raise a fault in the hardware that may be reported to asoftware monitor to deal with memory violations.

FIG. 5 is a flowchart of a method performed by a consumer of cloudservices in accordance with one embodiment of the invention. In “Requesta Service from Cloud Services Provider” block 502, the consumer requestsa service from the cloud services provider. For example, the request maybe for virtualization services, or the request may be to perform atransaction for which the cloud services provider will establish avirtual machine or other process to perform the transaction.

The cloud services provider identifies a key domain-capable server orgroup of servers to service the consumer's request. In “Receive DomainManager Image and Memory Position-Dependent Address Information fromCloud Services Provider” block 504, the consumer receives a domainmanager image and memory position-dependent address information, alsoreferred to herein as fix-up variable information, from the cloudservices provider. The memory position-dependent address informationspecifically identifies physical locations in memory of the server(s)that are servicing the consumer's request. This memoryposition-dependent address information may include physical addresses ofpages in memory, physical addresses for page tables, control registerinformation (e.g., CR3 values), interrupt descriptor table registerinformation, etc. for the server(s) that are servicing the consumer'srequest. The domain manager image may contain page table structure(s)that map linear/virtual addresses of the domain manager image to thephysical addresses where the domain manager image is to be located inmemory of the cloud services provider's server.

Control then passes from “Receive Domain Manager Image and MemoryPosition-Dependent Address Information from Cloud Services Provider”block 504 to “Measure Domain Manager Image” block 506, where theconsumer measures the domain manager image to ensure that the domainmanager image has not been compromised. The consumer may verify thedomain manager image using known whitelisting techniques, such ascomputing a hash of the domain manager image and comparing the hashvalue to a master hash value for a master domain manager image (that isknown to be uncorrupted); source code can be checked and recompiled intoa matching image; government certification of the image may be verified;the image may be confirmed to be consistent with open source software,etc. An image is considered to be trustworthy if the image will not leakconsumer data. For example, an image may be considered trustworthy ifall communications are secured using the consumer's secret keys, andfiles/memory pages are encrypted and integrity checked when saved and/orrestored to or from storage.

From “Measure Domain Manager Image” block 506, control passes to“Verified?” decision point 508. If the domain manager image is notverified, control passes to “Error” block 522, where the consumerhandles the situation where the cloud provider's domain manager imagehas not been verified. In such a situation, the consumer may choose notto use that particular public cloud services provider's services.

If the domain manager image is verified at “Verified?” decision point508, control passes to “Create Domain Launch Image” block 510. At block510, the consumer creates a domain launch image, which will be executedon the cloud services provider's server to “launch” a key domain.Launching a key domain may include, for example, creating a key domain,causing hardware to encrypt the data stored in memory locationsbelonging to the key domain with a key domain key, and storing data(such as code to be executed to initially establish the key domain) inthe memory locations belonging to the key domain.

In one embodiment, the consumer uses the memory position-dependentaddress information provided by the cloud services provider in “ReceiveDomain Manager Image and Memory Position-Dependent Address Informationfrom Cloud Services Provider” block 404 to modify the provider-supplieddomain manager image as part of the code to be executed to launch thekey domain. For example, the consumer may modify the domain managerimage's page tables so that the physical addresses in the page tablesare updated (fixed up) given the physical memory addresses where thedomain manager image is to be located. Once the paging structures areupdated, all the linear/virtual addresses used by the executing domainmanager image's code, data, and programs will map to the correctcorresponding physical memory addresses on the cloud service provider'sserver. In one embodiment, the consumer encrypts a fixed-up domainmanager image using the consumer's key domain key and creates integritycheck values (ICVs) for the encrypted fixed-up domain manager imageusing the consumer's key domain key.

In one embodiment, the consumer creates a domain launch image includingthe encrypted fixed-up domain manager image for distribution to thecloud services provider server. The consumer also includes secret keysin the domain launch image for paging, migration, attestation,communications, and other functions provided by the executing domainprocess (e.g., VM, OS, etc.). When the domain launch image is encrypted,the corresponding page table structures contained within the domainlaunch image are also encrypted.

Because the domain launch image is encrypted (and integrity checked)using a memory position-dependent “tweaked” cipher, an adversary cannotmove parts of the domain launch image around in memory. The page tablesmap the domain launch image's programs and data to the correct physicalmemory addresses on the cloud services provider's server, so programbehavior cannot be maliciously changed given that the domain launchimage is cryptographically bound to the correct physical memorylocations. In other words, the domain launch image cannot be decryptedcorrectly if the domain launch image is not loaded into the correctphysical memory locations on the cloud services provider's server.Furthermore, integrity check values can detect any attempts to modifythe domain launch image contents and/or the location in memory intowhich the domain launch image is loaded.

Control passes from “Create Domain Launch Image” block 510 to “VerifyKey Domain-Capable Server's/Group's Certificate and Obtain KeyDomain-Capable Server'/Group's Public Key” block 512.

In block 512, the consumer verifies the identified cloud servicesprovider server's/group's certificate, and obtains the identified keydomain-capable server's/group's public key.

Control passes from block 512 to “Exchange Key Domain Key with VerifiedKey Domain-Capable Server(s)” block 514. The consumer exchanges a keydomain key with the key domain-capable server(s) verified in block 512.One aspect of the exchange of the key domain key is that the key domainkey is provided only in encrypted form by the consumer directly to thehardware (such as memory encryption engine 415 of FIG. 4) of the keydomain-capable server. Because the key domain-capable server's softwaredoes not receive the key domain key, the key domain-capable serversoftware cannot decrypt the contents of the key domain withoutrequesting the hardware to perform the decryption. In one embodiment,the consumer uses the server's/group's public key obtained in block 512to encrypt the consumer's key domain key before providing the encryptedkey domain key to the hardware of the key domain-capable server.

In another embodiment, the key domain key may be negotiated between theconsumer and the server hardware. The key domain key may be generateddirectly with hardware (e.g., microcode, firmware, CSME, SMM), where theserver hardware can provide its unique (or group) identity and publickey/CERT, and then a Diffie Hellman key exchange (or RSA) can completethe key domain key exchange with the consumer. This embodiment requiresthe consumer to be online to perform the key exchange at the time thatthe domain image is launched.

This key exchange enables the virtual machine running on the verifiedkey domain-capable server to access domain launch image data encryptedwith the consumer's key domain key without exposing the key domain keyitself. Encrypted messages are passed through the cloud servicesprovider's software stack on the key domain-capable server. The keydomain-capable server hardware provides a cryptographic endpoint for thecommands. For example, the consumer can encrypt a key that it uses forthe key domain with the server's public key, and send this encrypted keydomain key to the cloud services provider. The cloud services providerthen could issue an instruction, such as a Create Key Domain (CreateKD)instruction, on the key domain-capable server hardware to create the newkey domain. In addition, the provider can also use the same Create KeyDomain (CreateKD) instruction to recreate a key domain, for example, ifa VM has been suspended and is to be resumed.

Control passes from “Exchange Key Domain Key with Verified KeyDomain-Capable Server(s)” block 514 to “Encrypt Launch Image includingDomain Manager Image for Key Domain-Capable Server that Exchanged KeyDomain Key” block 516. Once a key domain key is established (or before,as it is the consumer's key), the consumer uses the key domain key toencrypt a domain launch image including the domain manager image for thespecific server with which the consumer exchanged the key domain key.The consumer encrypts the domain launch image given memoryposition-dependent address information provided as the fix-up variableinformation by the cloud services provider. In one embodiment, anencryption technique called a tweakable block cipher is used. Atweakable block cipher accepts a second input, called a tweak, alongwith plaintext or ciphertext input to be encrypted. The tweak, alongwith the key, selects the permutation computed by the cipher. Inencrypting the consumer's domain launch image, the key domain-capableserver's physical memory address is used as the tweak, making theresulting encrypted launch image memory position-dependent. Theencrypted launch image is described as memory position-dependent becausethe encrypted launch image must be loaded into the correct physicalmemory addresses of the cloud services provider's server before it canbe correctly decrypted.

In one embodiment, the domain launch image is encrypted using XEX-basedtweaked codebook mode with ciphertext stealing (XTS). The consumerencrypts the domain launch image in memory position-dependent XTS modeusing page address tweaks and the key domain key. The correct physicaladdresses of where the domain launch image will be loaded are includedin the XTS tweak for each block encrypted. Other tweakable ciphers mayalso be used in other embodiments, such as Liskov, Rivest, and Wagner(LRW) or counter mode cipher.

The consumer may also calculate integrity check values (ICVs, such askeyed-hash message authentication codes (HMACs)), for the domain imageusing the key domain key. In one embodiment, integrity check values arealso memory position-dependent so that the address/memory location ofthe corresponding data line in memory is taken into account in verifyingthe integrity of the data. The consumer may include the ICV values inthe encrypted launch image in a situation where the consumer knows theaddress locations of the ICV table on the server corresponding to theconsumer's encrypted launch image. The ICVs values table could also beencrypted with the key domain key using a tweak indicating the correctserver memory addresses for the ICV table. The cloud services providerserver would then load the ICV portion of the encrypted launch imageinto the correct slots of the ICV table at those same server memoryaddresses for the ICV table.

From “Encrypt Launch Image including Domain Manager Image for KeyDomain-Capable Server that Exchanged Key Domain Key” block 516, controlpasses to “Establish Key Domain with Key Domain-Capable Server” block518. In block 518, the consumer sends a request to create a key domainto the key domain-capable server. This request may include the encryptedkey domain key, which serves as an input value for a Create Key Domain(CreateKD) instruction to be executed by the processor of the keydomain-capable server. The key domain selector/identifier to use is alocal decision made by the cloud service provider's memory manager, asthe cloud service provider's memory manager needs to manage a limitedkey domain namespace. The consumer does not need to know the key domainselector/identifier, and the value of the key domain selector/identifiercan be changed by the cloud services provider to avoid local conflicts.The actual key domain key provides security for the consumer's VM imagewhile the key domain selector/identifier tells the cloud servicesprovider server's hardware in which slot/register the key domain key iscurrently locally stored.

From block 518, control passes to “Send Encrypted Domain Launch Image toKey Domain-Capable Server(s)” block 520. The encrypted domain launchimage is sent to the cloud services provider, and the cloud servicesprovider's software stack on the key domain-capable server loads thedomain launch image into memory (i.e., into a k-bit off (i.e.,unencrypted) region of memory), at the correct physical memoryaddresses.

FIG. 6 is a flowchart of a method performed by a cloud services providerin accordance with one embodiment of the invention. Control begins at“In Response to Consumer's Request for Services, Provide Consumer withDomain Manager Image” block 602. The consumer's request may bespecifically for virtualization services, or the consumer's request maybe to perform a transaction that the cloud services provider willperform via a virtual machine or other process for the consumer.

Control proceeds from “In Response to Consumer's Request for Services,Provide Consumer with Domain Manager Image” block 602 to “Allocate Spacefor Domain Manager Image and Provide Memory Position-dependent AddressInformation to Requesting Consumer” block 604. In this block, the cloudservices provider allocates space in memory for the domain managerimage, and notifies the requesting consumer of memory position-dependentaddress information for the allocated memory space. This memoryposition-dependent address information may include, inter alia, physicaladdresses of pages in memory, physical addresses for page tables,control register information, interrupt descriptor table registerinformation, etc.). The memory position-dependent address informationmay also include an expected entry point. As an alternative embodiment,the cloud services provider can create an already fixed-up domain imagethat the consumer can re-verify as correct.

As mentioned above with reference to “Request a Service from CloudServices Provider” block 502 of FIG. 5, the cloud services provider mayidentify a group of servers that can provide key domain capabilities.For example, each server in a group of servers may use the same key,referred to as a group key, such as Direct AnonymousAttestation/Enhanced Privacy Identifiers (DAA/EPID)'s group publicverification key. DAA is a digital signature algorithm supportinganonymity. Unlike traditional digital signature algorithms, in whicheach entity has a unique public verification key and a unique privatesignature key, DAA provides a common group public verification keyassociated with many (typically millions) of unique private signaturekeys. DAA was created so that a device could prove to an external partywhat kind of device it is (and optionally what software is running onthe device) without needing to provide device identity, i.e., to provethat the device is an authentic member of a group without revealingwhich member. EPID enhances DAA by providing an additional utility ofbeing able to revoke a private key given a signature created by thatkey, even if the key itself is still unknown.

From block 604, control proceeds to “Exchange Key Domain Key withConsumer” block 606, where the key domain-capable server obtains the keydomain key from the consumer. The key domain key is provided by theconsumer as an encrypted key, where the consumer's key domain key hasbeen encrypted with the key domain-capable server's public key. In oneembodiment, a memory manager of the key domain capable-server causes theencrypted key domain key to be written into a slot/register of the keydomain-capable server and a memory encryption engine (such as memoryencryption engine 415 of FIG. 4) reads the encrypted key domain key fromthe slot/register and decrypts the key domain key using the keydomain-capable server's private key.

From block 606, control proceeds to “In Response to Consumer Provisionof Domain Launch Image, Load Domain Launch Image into Allocated Space inMemory” block 608. When the consumer provides a VM workload to the keydomain-capable server, the consumer provides the domain launch image,encrypted with the consumer's key domain key. The key domain-capableserver loads the domain launch image into the physical memory spaceallocated in block 604. The domain launch image is installed in physicalmemory on the cloud services provider's server at the physical memorylocation communicated to the consumer via the memory position-dependentaddress information. Shared, unencrypted memory locations can be madeavailable by the cloud services provider (e.g. using a portion of thephysical address, such as k-bit) for initially loading this encryptedlaunch image in memory.

Because multiple servers may share the same public key, identifyingmemory position-dependent address information may require resolution ofmemory conflicts between the multiple servers. In one embodiment, memorylocation conflicts between the multiple servers in a group are resolvedbecause the image that is position-dependent in the server's memory isthe consumer's domain launch image, which can be transient. That is, thedomain launch image is used to launch the consumer's larger domain (VM)image, which can be paged anywhere in memory selected by the cloudservices provider. After the consumer's larger domain image is launched,the position-dependent portion of the encrypted image can be removedfrom memory (having performed the function of launching the consumer'slarger domain image). Thus, memory usage can be managed by the cloudservices provider, which makes space for the position-dependent launchimage, uses the position-dependent launch image to launch the rest ofthe domain image into variable memory, and then frees the space occupiedby the domain launch image (e.g. to make room for a different domainlaunch image for a different key domain that happens to overlap withthose same memory locations).

The consumer's domain image can be launched in multiple phases, undersoftware control. The first phase is executing the domain launch image,which is encrypted by the consumer in accordance with the memoryposition-dependent address information. The second phase is launchingthe rest of the consumer's domain image, which is not required to beloaded into particular physical memory locations on the cloud servicesprovider's server.

From block 608, control proceeds to “Create and Initialize Key Domain inMemory” block 610. In one embodiment, the key domain-capable serverreceives a request to create a key domain from the consumer. Thisrequest may include the encrypted key domain key, which may serve as aninput value for a Create Key Domain (CreateKD) instruction to beexecuted by the key domain-capable server. The CreateKD instruction mayalso initialize the new key domain by quiescing processor cores,flushing caches and translation look-aside buffers (TLBs) of old keydomains, and initializing a memory encryption engine with the new keyfor the key domain. Initializing the memory encryption engine with thenew key domain key may include writing the key domain key to a memoryslot/register accessible by the memory encryption engine hardware.Alternatively, these initialization functions may be performed via aseparate Initialize Key Domain (InitKD) instruction.

From block 610, control proceeds to “Measure Domain Launch Image” block612. The cloud services provider verifies that the expected domainmanager image is present within the consumer's encrypted domain launchimage. This verification ensures that privileged code such as VMX-rootcomponents and data structures were included in the consumer's encrypteddomain launch image.

In one embodiment, a memory manager uses a hash key domain (HashKD)instruction to verify that the domain launch image's pages contain theprovider's domain manager (VMMlet) image. A “secure hash” function, suchas the Secure Hash Algorithm 3 (SHA3) defined by the National Instituteof Standards and Technology (NIST), is used to compute a hash value forthe provider's domain manager image within the encrypted domain launchimage. Secure hash algorithms transform data using a hash function,which may be an algorithm that includes bitwise operations, modularadditions, and compression functions. The hash function then produces afixed size string that looks nothing like the original input string.These algorithms are designed to be one-way functions, meaning that oncethe original input data has been transformed into hash values, it isvirtually impossible to transform the hash values back into the originalinput data.

The cloud services provider can verify that the domain manager image ispresent within the consumer's domain launch image by constructing thedomain manager image from the consumer's encrypted domain launch imagein local memory. The cloud services provider can then perform the sameverification function (i.e., hash function) that the HashKD instructionuses on the contents of the local memory locations for the constructeddomain manager image. If the verification function (hash) values of thecontents of the local memory locations match results of the hash KDinstruction, the cloud services provider can be assured that theprovider's domain manager image was correctly incorporated as part ofthe consumer's encrypted domain launch image.

In one embodiment, the HashKD instruction can provide a hash value for acache line, or, in another embodiment, the HashKD instruction canprovide a hash value for up to a page of memory at a time.

In one embodiment, the HashKD instruction provides only hash values sothat no consumer secrets in the domain launch image are revealed to thecloud services provider. The consumer's secrets can be in theVMX-non-root portion of the domain launch image, e.g., as part of theoperating system running above the domain manager (VMMlet). Providingonly hash values as a result of the HashKD instruction enables the cloudservices provider to verify only the provider's portion (the domainmanager image portion) of the encrypted domain launch image.Verification of the provider's portion independently of theconsumer-modified (including consumer secrets) portion of the encrypteddomain launch image prevents disclosure of consumer's secrets to thecloud services provider.

From block 612, control proceeds to “Verified?” decision point 614. Ifthe domain launch image measurement was not verified, control proceedsto “Error” block 626, where the cloud services provider may report theverification failure to the consumer. If the image measurement wasverified at “Verified?” decision point 614, control proceeds to “ExecuteConsumer's Domain Launch Image and Verify Entry Point” block 616.

At “Execute Consumer's Domain Launch Image and Verify Entry Point” block616, the key domain-capable server's stack will execute the consumer'sdomain launch image at the expected entry point (as was provided via thememory position-dependent address (“fix-up variable”) information to theconsumer). A memory manager VM loads the consumer-encrypted domainlaunch image into unencrypted memory pages (with k-bit disabled). A newkey domain is initiated.

In one embodiment, the key domain-capable server's processor executes aSwitch Key Domain (SwitchKD) instruction, providing as input thedestination key domain identifier/selector, an entry point address, andcontrol register information. In addition, in one embodiment, akeyed-hash message authentication code (HMAC) calculated by the consumer(e.g., using the key domain key or a derivative thereof) is used toverify that the entry point address and control register information arecorrect.

Prior to executing the domain launch image, the key domain-capableserver may turn interrupts off. In one embodiment, the first instructionexecuted after switching key domains is a special ENDBRANCH-likeinstruction denoting the expected entry point for a key domain switch.The destination domain manager (VMMlet) code after the ENDBRANCHKDinstruction verifies that the VMM is in protected mode. The destinationdomain manager (VMMlet) code also verifies that control registers andinterrupt descriptor table registers, etc. are correct. The destinationdomain manager (VMMlet) code then re-enables interrupts and resumesexecution from a saved state.

In one embodiment, the SwitchKD instruction is implemented using an HMACfunction to verify the consumer's domain launch image. Thisimplementation is the preferred embodiment of SwitchKD, as it is themost flexible. The consumer can use a secret established with the serverhardware, e.g. the key domain key or a derivative thereof, to calculatean HMAC (e.g. SHA3 HMAC) over the expected processor state for enteringthe key domain (e.g. verify the processor's registers for theinstruction pointer, the stack pointer, CR0, CR3, CR4, IDTR, GDTR, LDTR,any MSRs that can impact the security of the VM, etc.). The HMACimplementation of the SwitchKD instruction can be establisheddynamically by the consumer's domain image, and multiple entry pointscan be supported by computing multiple HMACs, one for each unique validentry point into the consumer's domain image. This flexibility todynamically define new entry points using the HMAC allows the server tostart with the original encrypted domain launch image, execute theoriginal encrypted domain launch image at a fixed initial entry point,then internally (from within the key domain) copy that domain launchimage to new dynamically assigned memory locations (in accordance withthe provider's memory management policies), and a new entry pointlocation established for the new dynamically assigned memory locations.Now the original domain launch image, and the static memory locations towhich the original domain launch image is cryptographically bound, canthen be freed by the cloud services provider leaving only thedynamically reassigned VM image in memory at the locations dynamicallydefined by the provider's memory manager software. In this way, even ifmultiple initial launch images for different consumers happen to overlapin memory, they can be loaded sequentially, transitioning to dynamicmemory locations, freeing that domain launch image's memory locationsfor the next consumer's domain launch image and so on, with eachexecuting domain image re-computing HMACs using the consumer's keydomain key for the new entry points as each dynamic image is created.

Alternatively, when creating a new key domain (CreateKD), the entrypoint values (instruction pointer registers, stack pointer registers,control registers, interrupt descriptor table registers, etc.) can beestablished by the consumer with the key domain-capable server, andverified by the cloud services provider.

When the key domain-capable server executes the domain launch image, thepage tables are referenced by the processor's control register (i.e.,CR3) that specifies the physical address for the root of the page tablestructure. The control register must be set to the correct value onswitching into the key domain. In one embodiment, a Switch Key Domain(SwitchKD) instruction includes a keyed hash parameter, such as an SHA3HMAC. The keyed hash parameter is used to assure that operationally thecorrect page table structure within the image is used by the cloudservices provider server's processor when executing the domain launchimage (and thus, that all the memory mappings are correct.) The keyedhash parameter is used to confirm that the cloud services provider'sserver processor state is correct when entering the domain launch image,as the processor will validate the keyed hash parameter (HMAC) againstthe cloud services provider server's processor control register state,instruction pointer, stack pointer, etc.

From “Execute Consumer's Domain Launch Image and Verify Entry Point”block 616, control proceeds to “Load Rest of Consumer's Domain Imageinto Memory” block 618. The key domain-capable server loads remainingportions of the consumer's domain image into memory. The remainingportions of the consumer's domain image may include, for example, therest of a domain image 2532 of FIG. 25, including operating system(s),application(s), scripts, or other code.

From “Load Rest of Consumer's Domain Image into Memory” block 618,control then proceeds to “Verify Additional Pages of Consumer's DomainImage using Secret Keys included in Domain Launch Image” block 620. Therunning verified domain image now can verify additional pages of theconsumer's domain image using secret keys from the domain launch image.For example, the domain launch image may include secret keys for paging,migration, attestation, communications, and other functions.

From “Verify Additional Pages of Consumer's Domain Image Using SecretKeys Included in Domain Launch Image” block 620, control proceeds to“Perform Secure Operations within Consumer Key Domain” block 624. Oncethe consumer domain (VM) image has been properly executed and thecorresponding key domain has been switched, the domain manager cancomplete loading an operating system and request additional resources(memory pages, IO resources, etc.) from the cloud services provider'smemory manager. Save and restore memory operations (involving, e.g. theVM control structure, control registers, etc.) stay inside the keydomain, are performed directly by the memory encryption engine hardware,and are not exposed to the cloud services provider. Because the domainmanager image originated as the cloud services provider's software, onceverified, the executing domain manager will obey memory manager commandsand cooperate with other domain managers. In addition, like a normalVMM, the domain manager will protect the server's hardware and resourcesfrom the rest of the consumer domain's less privileged code, such as anoperating system, applications, etc.

FIG. 7 is a diagram showing components of a consumer domain image (e.g.,a consumer VM image) in accordance with one embodiment of the invention.Consumer domain image 710 includes a static provider-supplied domainmanager portion 712 and a dynamic consumer-supplied portion 714. In oneembodiment, static provider-supplied domain manager portion 712corresponds to a domain manager (VMMlet), which is privileged code thatinstantiates and manages consumer virtual machines. The staticprovider-supplied domain manager portion 712 may also issue a command tothe cloud provider service's hardware to create a key domain, providingthe consumer's encrypted key domain key to be used to encrypt memorylocations belonging to the newly-created key domain. The staticprovider-supplied domain manager portion 712 may also issue a command tothe cloud provider service's hardware to switch to a different keydomain, providing the consumer's encrypted key domain key for the keydomain to which control is to be switched. A virtual machine managed bythe domain manager (VMMlet) may then be caused to operate within thecurrently active key domain. The domain manager (VMMlet) privileged codecan be measured and verified by the consumer, thereby enabling theconsumer to trust the domain manager (VMMlet) privileged code as part ofits Trusted Computing Base.

To establish the consumer domain image 710 in memory of the cloudprovider server, the consumer creates an encrypted domain launch imagethat is executed in the memory of the cloud provider server. The domainlaunch image may contain only the basic code needed to (1) cause thecloud services provider server hardware to create a new key domain orswitch to an existing key domain within memory of the cloud servicesprovider server and (2) cause some baseline code to operate within thatkey domain. For example, the domain launch image may create a newvirtual machine or cause an existing virtual machine to access datawithin the memory locations of the key domain established by the portionof code provided in (1).

The domain launch image is created by the consumer as it would appear indesignated memory locations of the cloud services provider server'smemory. For example, the consumer may encrypt the domain launch imagewith the consumer's key domain key using a memory position-dependentcipher to cryptographically bind the domain launch image into thedesignated memory locations of the cloud services provider server'smemory. Once the encrypted domain launch image is loaded into the memorylocations designated by the memory position-dependent cipher, theexecuting encrypted domain launch image can then bootstrap dynamicallyloading additional domain image code (such as dynamic consumer-suppliedportion 714 code) into the consumer's domain image 710. In oneembodiment, dynamic consumer-supplied portion 714 corresponds to theconsumer domain image's less privileged code, such as an operatingsystem, applications, etc.

In one embodiment, the consumer's encrypted domain launch image includesat least the domain manager (VMMlet) privileged code. In at least oneembodiment, the consumer's encrypted domain launch image also includessome consumer-supplied code.

Because the domain launch image is encrypted by the consumer using theconsumer's key domain key in the consumer's own environment, theexecuting encrypted static portion 712 can be described as being made“externally” to the key domain. Because only the consumer knows the keydomain key, the cloud services provider cannot create, add code to, ormodify the consumer's encrypted domain launch image without corruptingthe consumer's encrypted domain launch image.

Once code included in the consumer's domain launch image begins toexecute on behalf of the consumer within the key domain, the executingconsumer's domain launch image code can take over and extend theconsumer's domain image 710. Extending the consumer's domain image 710includes, for example, dynamically adding new code (such as dynamicconsumer-supplied portion 714) to the consumer's domain image 710. Newcode can be added to and/or modifications can be made to the consumer'sdomain image 710 from within the key domain using a protocol determinedby the consumer (e.g., the consumer's domain image 710 may be extendedonly after new extension code segments are verified).

As the consumer's domain image 710 writes to memory from within the keydomain, data from those memory write operations is encrypted and tweakedwith the memory addresses by the memory encryption engine. Read andwrite operations performed from within the key domain are therefore alsolocation-dependent because they are created from code executing withinthe key domain. Such operations can be described as being made“internally to the key domain” by the memory encryption engine. In otherwords, the cloud services provider software executing outside the keydomain cannot modify or rearrange this dynamically-created portion ofthe consumer domain image.

In one embodiment, a consumer domain image that has been extendeddynamically can be converted to a static version of the consumer domainimage. For example, converting from a dynamic to a static consumerdomain image could be performed when execution of a virtual machineinstantiated from the consumer domain image has been suspended and is tobe resumed. A copy of the dynamic consumer domain image could becaptured at the time the virtual machine is suspended, the copy of thedynamic consumer domain image could be flushed to memory, and ciphertextbound to the addresses from memory could be saved. The consumer couldrecalculate any integrity check values associated with the memoryaddresses and re-create the consumer domain image to incorporate thoseintegrity check values. The re-created consumer domain image could bere-launched as a static consumer domain image when the virtual machineis to be resumed.

As described with reference to FIGS. 5 and 6, the encrypted domainlaunch image created by the consumer includes a consumer domain manager(VMMlet) image, which is a modified version of the cloud servicesprovider-supplied domain manager (VMMlet) image. The provider-supplieddomain manager (VMMlet) image is modified to incorporate memoryposition-dependent address information for a designated server of thecloud services provider. The consumer domain manager image is staticallybound to the designated server and the designated server's memoryaddresses, which means that the consumer domain manager image must beinstalled and executed at a designated memory address of the designatedserver in order to function properly.

The cloud services provider executes the consumer's encrypted domainlaunch image (containing the consumer's domain manager (VMMlet) image),which causes an initial static domain manager image to be installed at adesignated static memory address of the designated server. The initialstatic domain manager image is executed on the cloud services provider'sserver as a consumer domain manager (VMMlet). The consumer domainmanager (VMMlet) manages virtual machines on behalf of the consumer bycausing code of the consumer's VM image to be loaded into memory andexecuted as a consumer domain (VM). A consumer domain (VM) performsoperations on data in the server's memory through the server's memoryencryption engine. A memory footprint for the consumer domain (VM) imagedynamically grows and shrinks as contents of the consumer domain (VM)image dynamically change.

FIG. 8 is a diagram showing a data physical address 870 in accordancewith one embodiment of the invention. Data physical address 870 may beused to determine a key or a tweak, discussed above.

As described above, a key domain can be defined using unused physicaladdress bits 874 (also referred to as alias bits 874) of the dataphysical address 870 (or, alternatively, other metadata passed through acache). For example, because there will likely be less physical memoryinstalled in a system than can be addressed using a 64-bit physicalmemory address, the unused most significant address bits 874 can be usedto select between different “key domains.” As described above, the term“key domain” refers to a set of memory locations that are encrypted witha common key domain key. Unused bits of the data physical address 870may be used to determine, for example, which key and/or tweak is to beused when encrypting and/or decrypting memory for a physical memoryaddress. Different keys can be selected for the same data physicaladdress 870 based on unused address/alias bits 874. For example, theencryption technique XTS (XEX-based tweaked-codebook mode withciphertext stealing) may use the unused address/alias bits 874 for atweak for the same physical memory location, where different addressaliases may result in different ciphertext even if the data is the same.

The remaining bits 876 of the data physical address are used to identifythe physical memory address of the location in memory where the data isstored. Although two key domain addresses can alias to the same externalmemory location, when data from the physical memory location is readinto a cache, the cache holds the key domain addresses independently atthe full address resolution (e.g., including the full 64-bit physicalmemory address).

Different keys can be selected based on unused address bits (e.g., XTSmay use the alias bits for a tweak for the same physical memorylocation), where different address aliases may result in differentciphertext even if the data is the same.

Because the unused address bits 874 alias to the same physical addressin memory for a key domain when there are unused address bits due tounpopulated memory, the key domain selector can be set to the value ofthe unused address bits. Alternatively, the key domain selector can beset to zero if data in the physical address in memory is to be shared(i.e., not limited to a particular key domain).

In one embodiment, “k-bit” field 872 represents one bit of the dataphysical address 870, in this case, the upper-most bit of the dataphysical address 870. The k-bit can be set by a domain manager (VMMlet)or by a virtual machine (VM) in page tables or extended page tables toindicate whether data resulting from a memory access should be encryptedwith the corresponding key domain key. When k-bit=0, the k-bit is saidto be disabled and data resulting from the memory access are notencrypted by the key domain key (although it is possible that the datamay be encrypted using a shared key). When k-bit=1, the k-bit is said tobe enabled and results of the memory access are encrypted with the keydomain key. The k-bit field 872 can also be used to designate a range ofmemory that is shared and does not require key domain encryption. In analternative embodiment, the k-bit can be additional metadata associatedwith cache lines and carried through the cache rather than a componentof the data physical address.

In the scenario when a system has sufficient installed memory such thatall the address bits of data physical address 870 are used (with theexception of the one k-bit 872), the key domain addresses consume aphysical range of the total populated memory (corresponding to the keydomain's physical address bits) when k-bit is true/enabled. When k-bitis off/disabled, the key domain selector bits 874 reference all thememory ranges, but as plaintext (or shared), such that all populatedmemory is addressable as shared memory.

FIG. 9 is a diagram showing virtual to physical memory mapping inaccordance with one embodiment of the invention. Many computer systemstoday use virtual memory systems to manage and allocate memory tovarious processes running within the system. Virtual memory allows eachprocess running on the system to operate as if it has control of thefull range of addresses provided by the system. The operating system(OS) maps the virtual address space for each process to the actualphysical address space for the system. Mapping from a physical addressto a virtual address is typically accomplished through the use of pagetables.

The term “address space” is used herein to mean a set of addresses inmemory corresponding to a given process or virtual machine (VM), and an“address space identifier (ASID)” may be any number, code, or othernotation which identifies one or more address spaces with which the ASIDis associated.

FIG. 9 represents the case where there is no aliasing; i.e., sufficientmemory is available in the system such that the key domain selectoraddress bits 974 are used together with the page address 976 and cacheline selector 978 to select an actual physical memory locationreferenced by data line physical address 975. Here, each individual keydomain will be located in a non-overlapping range of physical memory920.

FIG. 9 shows a virtual address to physical address mapping in accordancewith an embodiment of the invention. A physical address 924 within aphysical page 822 in a physical memory 920 may be addressed using avirtual address 900. As shown, virtual address 900 includes a number offields to index a multi-level paging structure 960 to access physicaladdress 924, which addresses a particular physical page 922 within aphysical memory 920. Note that multi-level paging structure 960 is justone example of a multi-level paging structure for accessing a physicalmemory location. While multi-level paging structure 960 is describedwith reference to a 64-bit virtual address, different page tablestructures may be used for 32-bit virtual addresses, Physical AddressExtension (PAE) extended mode addresses, or other types of virtualaddresses.

In virtual address 900, an offset field 902 (such as bits 0-11 of a64-bit address) is used to address the physical address 924 (as shown bypointer 903) within a physical page 922 of physical memory 920. A pagetable entry field 904 (entitled “table,” such as bits 12-20 of a 64-bitaddress) addresses a page table entry 932 (as shown by pointer 962 c) ina page table 930. A page directory entry 906 (entitled “directory,” suchas bits 21-29 of a 64-bit address) addresses a page directory entry 942(as shown by pointer 962 b) in a page directory 640. A page directorypointer 909 (entitled “PDP,” such as bits 30-38 of a 64-bit address)addresses a page directory pointer entry 952 (as shown by pointer 962 a)in a page directory pointer table (PDPT) 950. The base address of OSpaging structure 960 may be accessed using a pointer 961 in a controlregister, such as CR3. In such manner, a 64 bit linear address may beused to implement a multi-level paging 9 structure to access a physicaladdress.

FIG. 9 also shows components of a data physical address 970corresponding to physical address 924 of physical page 922 of physicalmemory 920. “K-bit” field 972 represents one bit of the data physicaladdress 970, in this case, the upper-most bit of the data physicaladdress 970. The k-bit can be set by a domain manager (VMMlet) or by avirtual machine (VM) in page tables or extended page tables to indicatewhether data resulting from a memory access should be encrypted with thecorresponding key domain key. When k-bit=0, the k-bit is said to bedisabled and data resulting from the memory access are not encrypted bythe key domain key (although it is possible that the data may beencrypted using a shared key). When k-bit=1, the k-bit is said to beenabled and results of the memory access are encrypted with the keydomain key. The k-bit field 772 can also be used to designate a range ofmemory that is shared and does not require key domain encryption. In analternative embodiment, the k-bit can be additional metadata associatedwith cache lines and carried through the cache rather than a componentof the data physical address.

In data physical address 970, the “Unused Address Bits: Key DomainSelector” field 974 may represent a set of unused address bits that areused to distinguish between key domains. If the unused address bits oftwo data physical addresses have different values, then they alias tothe same physical address in memory. The “Page Address” field 976represents the address of the physical page 922 in physical memory 920.The “Cache Line Selector” field 978 represents a cache line within thepage referenced by “Page Address” field 976. Together, the “PageAddress” field 976 and the “Cache Line Selector” field 978 make up the“Data Line Physical Address” field 975, which represents the actualphysical location in physical memory 920. The “Cache Line Bytes” field979 contains the number of bytes in the cache line.

Referring now to FIG. 10, shown is another virtual address to physicaladdress mapping in accordance with an embodiment of the invention. Asshown in FIG. 10, an aliased guest physical address 1014 within analiased guest physical page 1012 in an aliased physical memory 1010 maybe addressed using a virtual address 1000. As shown, virtual address1000 includes a number of fields to index a multi-level paging structure1060 to access aliased guest physical address 1014, which addresses aparticular page 1022 within a physical memory location 1020. Note thatmulti-level paging structure 1060 is just one example of a multi-levelpaging structure for accessing a physical memory location. Whilemulti-level paging structure 1060 is described with reference to a64-bit virtual address, different page table structures may be used for32-bit virtual addresses, Physical Address Extension (PAE) extended modeaddresses, or other types of virtual addresses.

Aliased physical memory 1010 also includes aliased guest physical page1016, which represents a second range of aliased guest physical memory610 that is aliased to the same physical memory location 1022.

In virtual address 1000, an offset field 1002 (such as bits 0-11 of a64-bit address) is used to address the aliased guest physical address1014 (as shown by pointer 1003) within an aliased guest page 1012 ofaliased physical memory 1010. A page table entry field 1004 (entitled“table,” such as bits 12-20 of a 64-bit address) addresses a page tableentry 1032 (as shown by pointer 1062 c) in a page table 1030. A pagedirectory entry 1006 (entitled “directory,” such as bits 21-29 of a64-bit address) addresses a page directory entry 1042 (as shown bypointer 1062 b) in a page directory 640. A page directory pointer 1008(entitled “PDP,” such as bits 30-38 of a 64-bit address) addresses apage directory pointer entry 1052 (as shown by pointer 1062 a) in a pagedirectory pointer table (PDPT) 1050. The base address of OS pagingstructure 1060 may be accessed using a pointer 1061 in a controlregister, such as CR3. In such manner, a 64 bit linear address may beused to implement a multi-level paging structure to access a physicaladdress.

FIG. 11 is a diagram showing initial steps by a cloud services providerto provide a domain image to a consumer in accordance with oneembodiment of the invention.

In the example shown in FIG. 11, a memory manager 1140 of a cloudservices provider server including hardware 1110 allocates space 1114 inmemory 1112 for the domain image 1122, and notifies the requestingconsumer of memory position-dependent address (“fix-up variable”)information. This memory position-dependent address (“fix-up variable”)information may include, inter alia, physical addresses of pages inmemory (such as the physical addresses of the pages making up space1114), physical addresses for page tables, control register information,interrupt descriptor table register information, etc.). As analternative embodiment, the cloud services provider can create analready fixed-up domain image that the consumer can re-verify ascorrect. Specifically, the portion of the domain image that needs to bealtered is the physical memory page addresses in the page tables asshown in FIG. 9, page table entry 832. Page table entry 932 points tophysical page 922 in physical memory 920. The domain image can be viewedas a series of pages (e.g., 4 Kbytes each), with each page given aphysical page address (its location in memory). Image verification thencomprises checking that the virtual to physical mappings through thepage tables are correct given the contents of the pages comprising thedomain image.

FIG. 12 is a diagram showing messages between a consumer 1201 and acloud services provider's memory manager 1240 to provide a domainmanager image (such as VMMlet image 1122 of FIG. 11) to the consumer inaccordance with one embodiment of the invention.

In response to a consumer's request for service, software of a cloudservices provider's server (i.e., memory manager 1240) is configured toprovide a domain manager image (such as VMMlet image 1122 of FIG. 11) tothe consumer. The memory manager 1240 also sends memoryposition-dependent address information, also referred to herein asfix-up variable information, for the domain manager image to theconsumer. The consumer verifies that the domain manager image is validor uses a third party to verify that the domain manager image is valid.

After determining that the domain manager (VMMlet) image is valid asdescribed with reference to FIG. 11, the consumer use memoryposition-dependent address information identifying memory locationsprovided by the cloud services provider as fix-up variable informationto modify the verified domain manager image provided by the cloudservices provider to create a domain launch image to launch the domainmanager (VMMlet). Alternatively, the domain manager image may be“fixed-up” by the cloud services provider, so that the domain managerimage is prepared to run in the allocated memory locations.

In one embodiment, the consumer may also add the consumer's owncomponents, such as the consumer's secret keys for securecommunications, to the domain launch image. Having a method for securecommunication allows the consumer's basic domain launch image tosecurely retrieve the rest of the consumer's domain (VM) image from theconsumer using the consumer's secret keys. The consumer may also includethe consumer's own operating system, applications, etc., in the domainlaunch image.

Finally, when the consumer's domain launch image includes anyconsumer-supplied components, the consumer encrypts the domain launchimage. “Fixing up” the domain manager (VMMlet) image and creating theencrypted domain launch image is described further with reference toFIG. 13.

FIG. 13 is a diagram showing messages between components of a cloudservice environment to encrypt a domain launch image and establish a keydomain in accordance with one embodiment of the invention. As describedabove, the consumer 1301 modifies the verified domain manager imageprovided by the cloud services provider to create a domain launch imagefor the domain manager (VMMlet). The domain launch image is thenencrypted using a memory position-dependent “tweaked” cipher and theconsumer's key domain key.

The consumer 1301 may also calculate integrity check values (ICVs, e.g.,keyed-hash message authentication codes (HMAC) values) for the encrypteddomain launch image using the key domain key. The ICVs may be calculatedas position-dependent values and are used to verify the position as wellas the contents of the associated memory locations for the encrypteddomain launch image.

The consumer 1301 requests the cloud services provider memory manager1340 to identify a server in the cloud services provider's network thatprovides key domain management functionality. The cloud servicesprovider memory manager 1340 obtains a server certificate for a keydomain-capable server (in this example, from a server having CPU 1311)and provides the server certificate to the consumer 1301. The consumer1301 verifies that the server certificate is signed by an authoritycertifying that the identified server provides key domain managementfunctionality.

The consumer 1301 encrypts the consumer's key domain key with the cloudservices provider's key domain-capable server's public key correspondingto the key domain-capable server's certificate. The consumer 1301 sendsthe encrypted key domain key, encrypted launch image, and (optionally)integrity check values (ICVs) to the cloud services provider memorymanager 1340, which provides a Create Key Domain (CreateKD) command tothe CPU 1311 of the key domain-capable server. In one embodiment, thecloud services provider memory manager 1340 identifies a key domainaddress selector to use for the new key domain, providing the keyaddress domain selector to the CPU 1311 of the key domain-capableserver. The CPU 1311 of the key domain-capable server creates andinitializes a key domain. Initializing the key domain may includeflushing caches of any previous key domain (identified by the previouskey domain address selector) as well as flushing translation look-asidebuffers that cached address mappings for the previous key domain. As analternative to performing initialization functions as part of the CreateKey Domain instruction, the CPU 1311 of the key domain-capable servermay execute an Initialize Key Domain (InitKD) instruction to flush thecaches and translation look-aside buffers. The CPU 1311 of the keydomain-capable server may also provide the encrypted key domain key andkey domain address selector identifying the new key domain to a memoryencryption engine 1315 (shown in FIG. 13 as a Total Memory Encryptionengine with integrity, designated as TMEi 1315), although an alternativeembodiment is to use a Memory Encryption Engine (MEE)).

FIG. 14 is a diagram showing a consumer providing an encrypted launchimage for a domain manager (VMMlet) in accordance with one embodiment ofthe invention. As described above with reference to FIGS. 5, 12 and 13,a consumer encrypts a domain launch image using memoryposition-dependent address information provided by the cloud servicesprovider and a key domain key. In one embodiment, the consumer encryptsthe domain launch image in a memory position-dependent XTS mode usingpage address tweaks and the key domain key.

In FIG. 14, the consumer 1410 sends a fixed-up VMMlet 1462 (which is amodified version of the provider's original VMMlet 1022 of FIG. 10) aspart of an encrypted domain (VM) launch image 1460 to the cloud servicesprovider's memory manager 1440. The cloud services provider's memorymanager 1440 loads the Fixed-up VMMlet image 1462 of the encrypted VMlaunch image 1460 into the previously allocated memory space 1414 thathas been reserved (as space 1014 of FIG. 10) within shared memory 1412s. Because shared memory 1412 s is unencrypted memory pages (with k-bitdisabled), memory manager 1440 needs to ensure that the encrypted VMlaunch image is completely loaded into physical memory 1412 s and doesnot remain cache-resident. Writing the encrypted VM launch image 1460 tophysical memory 1412 s can be accomplished by either flushing theencrypted VM launch image 1460 from cache (e.g., using a CLFLUSHinstruction), or using uncached/write through/non-temporal memoryaccesses. These techniques for write operations assure that theconsumer's encrypted image data is directly written past a memoryencryption engine of hardware 1410 and into memory 1412 s (and does notremain cache resident).

FIG. 15 is a diagram showing messages between components of a cloudservice environment to load a consumer 1501 encrypted domain image intomemory 1512 of a key domain-capable server in accordance with oneembodiment of the invention. As described above with regard to FIG. 11,cloud services provider's software, such as a memory manager 1540 of thekey domain-capable server, loads the consumer-encrypted domain launchimage into unencrypted memory pages (with k-bit disabled) of memory1512. The cloud services provider's software (i.e., memory manager 1540)also writes ICVs for the encrypted domain image into an ICV table. TheICV table can be a protected range of memory 1512 managed and protectedby a memory encryption engine (TMEi) engine 1515. Write operations bysoftware components that are not part of memory manager 1540 to thisrange of memory addresses may be intercepted by the memory encryptionengine (TMEi) 1515, which can likewise configure the ICV values inmemory 1512.

Similarly, the memory encryption engine (TMEi) 1515 may prevent softwarefrom reading ICV values from this protected memory range to prevent thereplay of ICV values by malicious software. Only memory encryptionengine (TMEi) 1515 can read the ICV values once they have beenestablished. Preventing software from replaying ICV values prevents thereplay of dynamic domain image contents (e.g., the rest of theconsumer's domain image provided subsequent to the domain launch image).Static image contents (e.g., the domain launch image) can be replayedbecause the ICV values for the static image contents are provided by theconsumer.

The ICVs themselves provide an integrity check of the data and data'slocation (address), and the ICVs are keyed using the key domain key, orderivative thereof, used to encrypt the data line the ICV is checking.(For example, HMAC uses a secret key, as does Galois/Counter Mode (GCM)and IPHash.)

In one embodiment, a partial copy of the diffused cache line data is XTSencrypted with the key domain key to compute a secure ICV. In oneembodiment, ICV table entries are encrypted with the same key domain keyas the memory locations that they are used to integrity check.Encrypting both the ICVs and the data in memory locations that the ICVsprotect with the same key domain key cryptographically assures that theICVs belong to the same key domain as the data they protect.

The address selector for the key domain is also provided in unencryptedmemory (with k-bit disabled). The address also indicates the location inthe ICV table containing ICVs for the key domain when writing an ICVcomputed by the consumer using the consumer's key domain key to the ICVtable. (In other words, for every data line written to memory from theconsumer's encrypted Domain launch image, there is a correspondingintegrity check value written to the ICV table for that data line).

No key domain is used to write the consumer's encrypted domain launchimage data to memory 1512 (because the consumer's domain launch imagedata is already encrypted by the consumer). In other words, memorymanager 1540 may write the consumer's encrypted domain launch image toshared, unencrypted locations in memory 1512 without any additionalencryption. (Memory manager 1540 loads the consumer's encrypted imageinto memory 1512 so that when memory encryption is turned on with theconsumer's key (setting k-bit to 1 or “enabled,”) memory encryptionengine (TMEi) 1515 will properly decrypt the consumer's image whenreading it from memory 1512).

The CPU 1511 for the key domain-capable server obtains the addressselector for the key domain from the unencrypted locations in memory1512 and provides the address selector for the key domain to the memoryencryption engine (TMEi) 1515. The memory encryption engine (TMEi) 1515then writes the encrypted launch image to memory 1512 of the keydomain-capable server. Similarly, the CPU 1511 for the keydomain-capable server obtains the address indicating the location in theICV table containing ICVs for the key domain. The CPU 1511 provides thelocation of the ICV table containing ICVs for the key domain to thememory encryption engine (TMEi) 1515. The memory encryption engine(TMEi) 1515 then updates the ICV table in memory 1512 with the ICVs forthe key domain. Memory manager 1540 either flushes these values fromcache 1513 (e.g., by issuing a command to execute a CLFLUSHinstruction), or uses uncached/write through/non-temporal memory accessto assure the ICV data is directly written to memory 1512.

Updating the integrity check values (ICVs) for the key domain in thememory of the key domain-capable server is a write-only operation, suchthat the cloud services provider's software (memory manager 1540) cannotread the ICVs for the key domain. This write-only operation preventsreplay of dynamic image data. Only the domain launch image ICVs can bereplayed in-place (the consumer knowing the place because the consumercreated the encrypted launch image and ICVs). This functionality allowsthe provider to suspend, store and later resume VMs reusing theconsumer's domain launch image, without exposing additional ICVs, suchas those ICVs created dynamically as memory is updated by applicationsexecuting within a current key domain, to the cloud services provider'ssoftware (not even memory manager 1540).

FIG. 16 is a diagram showing the initialization of a key domain inaccordance with one embodiment of the invention. A memory manager 1640of the key domain-capable server can initialize the new key domain 1650by issuing an Initialize Key Domain (InitKD) command to the domainmanager (VMMlet) 1622. The InitKD command causes the CPU 1611 of the keydomain-capable server to execute an InitKD instruction, which quiescescores, flushes caches of old key domains, flushes all translationlook-aside buffers and address space identifiers (ASIDs) containing theold key domain mappings, and initializes the key domain-capable server'smemory encryption engine (TMEi) with the new key domain key for the keydomain address selector.

In one embodiment, initialization of a key domain is one of the actionsperformed by a Create Key Domain (CreateKD) instruction. References to aCreate Key Domain (CreateKD) instruction hereinafter may refer to aCreateKD instruction that not only creates a key domain from theserver's public key-encrypted key domain key, but also initializes thenew domain by quiescing cores, flushing caches of old key domains,flushes all translation look-aside buffers and address space identifiers(ASIDs) containing the old key domain mappings, and initializing the keydomain-capable server's memory encryption engine (TMEi) with the new keydomain key for the key domain address selector.

FIG. 17 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Create Key Domain operation inaccordance with one embodiment of the invention. In “Receive Create KeyDomain Command with Encrypted Key Domain Key” block 1710, the keydomain-capable server CPU receives a Create Key Domain command withinput parameters KD_Id, the local key domain identifier (key domainaddress selector), and Encrypted_Key, the encrypted key domain key.Control proceeds to “Decrypt Encrypted Key Domain Key Using Server'sPrivate Key, and Decrypt Optional Configuration Policy” block 1720,where the encrypted key domain key is decrypted using the server'sprivate key, a secret key that is unknown/unexposed to the cloudservices provider. Optionally, a configuration policy may also bedecrypted, again using the server's private key, or alternatively, ahash value of the policy data may be decrypted using the server'sprivate key. Control proceeds to “Decrypted Key Domain Key and PolicyValid?” decision point 1730. Examples of policy data that may beevaluated include the amount of memory a server is expected to haveinstalled, the encryption algorithms the server should use, that numberof CPUs that are socketed, whether hardware debug is allowed, etc. Thispolicy data is compared by hardware against the server's currentconfiguration to assure that the server's configuration is valid per theconsumer's expectations prior to using the consumer's key domain key. Ifthe decrypted key domain key and configuration policy are not valid,control proceeds to “Return Error” block 1740, where the CPU returns anerror in response to the Create Key Domain command.

At “Decrypted Key Domain Key and Policy Valid?” decision point 1730, ifthe decrypted key domain key and configuration policy are valid, controlproceeds to “Establish New Key Domain” block 1750. In establishing a newkey domain, the CPU of the key domain-capable server prevents other CPUsfrom using the key domain identifier or otherwise verifies that otherCPUs are not currently using the key domain identifier, flushes cachesfor the key domain identifier, flushes all translation look-aside bufferaddress space identifiers for the key domain identifier, and sets thecurrent key domain identifier and key domain key in the memoryencryption engine. Control then proceeds to “Assign ASID Tag for New KeyDomain Identifier and Resume” block 1760, where a new address spaceidentifier (ASID) tag is assigned for the new key domain identifier, andthe process issuing the Create Key Domain command is resumed.Furthermore, all processors are re-enabled if previously quiesced.

FIG. 18 is a diagram showing verification of a domain image inaccordance with one embodiment of the invention. A Verify Hash function1846 of the memory manager 1840 of a key domain-capable server verifiesthat the domain image (e.g., VMMlet 1822) for key domain 1850 is correctusing a Hash Key Domain (HashKD) instruction. Some values in the domainimage will be values for machine-specific variables/fixups (such asphysical addresses used in page tables). Hash values for thesemachine-specific variables can be virtually reconstructed (substitutingthe current address values) by the cloud services provider. When theresulting HashKD hash value matches the expected value for a hash of thedomain manager (VMMlet) provider/static portion of the image, both theconsumer and the cloud services provider agree that the domain launchimage is correct. Some other image locations may contain the consumer'ssecrets (keys/code/data, e.g. in the OS portion of the domain image).These locations can be hashed but the hash values will not disclose thememory plaintext (and thus the secret) to the cloud services provider.Hash values may have a minimum granularity, such as no less than a cacheline or no less than a page of memory (e.g. 4 KB).

When a secure VM executes for the first time, the secure VM may turn offthe HashKD functionality into its key domain, as the HashKD may be usedon initialization to read through a key domain, providing visibility tothe cloud services provider that the domain manager (VMMlet) wasproperly provisioned by the consumer. Otherwise, the HashKDfunctionality may not be needed.

FIG. 19 is a diagram showing messages between components of a cloudservices environment to verify a domain image in accordance with oneembodiment of the invention. In the first message, cloud servicesprovider software, such as a memory manager 1940 of the keydomain-capable server, requests a Hash Key Domain (HashKD) function tobe performed on memory locations where the consumer's encrypted launchimage for a domain manager (VMMlet) was installed. The CPU 1911 executesa Hash Key Domain (HashKD) instruction, providing the current addressselector identifying the key domain to be hashed, via cache 1913, to thememory encryption engine (TMEi) 1915. The memory encryption engine(TMEi) 1915 reads the encrypted data line from the memory locationswhere the encrypted launch image was installed, and the memoryencryption engine (TMEi) 1915 decrypts the data line using the key forthe key domain identified by the address selector. The memory encryptionengine (TMEi) 1915 sends the decrypted data to cache 1913, tagging thedecrypted data with the address and the key domain address selector. TheCPU 1911 for the key domain-capable server creates a hash value for thedecrypted data, stores the resulting hash value in a register of CPU1911 or in a memory location of memory 1912, and the cloud provider'ssoftware (i.e., memory manager 1940) verifies that the hash valuematches an expected hash value for the domain image originally providedto the consumer.

FIG. 20 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Hash Key Domain operation inaccordance with one embodiment of the invention. At “Receive Hash KeyDomain Command” block 2010, the CPU of the key domain-capable serverreceives a hash key domain command with input parameters of a key domainidentifier and physical address. Control proceeds to “Key DomainIdentifier and Address Valid?” decision point 2020, where the CPU of thekey domain-capable server determines whether the key domain identifierand physical address are valid. To make this determination, the CPU ofthe key domain-capable server may verify that the physical addresspoints to a memory location that is populated, and that there is a pagetable mapping and read permission for the physical address. The CPU ofthe key domain-capable server may also verify that the key domainidentifier has a corresponding key domain key installed in the memoryencryption engine (TMEi) for that key domain identifier. If the keydomain identifier and physical address are not valid, control proceedsto “Return Error” block 2030, where an error is returned to the issuerof the Hash Key Domain command. If the key domain identifier andphysical address are valid at “Key Domain Identifier and Address Valid?”decision point 2020, control proceeds to “Set Key Domain Identifier inPhysical Address, Set k-bit, Read Contents of Memory Location atPhysical Address” block 2040. The unused bits of a physical address areset to the key domain identifier, the value of the k-bit is set to 1 toindicate that encrypted data are to be read from the memory location atthe physical address, and the contents of the memory location at thephysical address are read by the memory encryption engine (TMEi) usingthe key domain key for the key domain identified by the key domainidentifier. When reading the contents of the memory location at thephysical address, the memory encryption engine (TMEi) decrypts thecontents using the key domain key. The memory encryption engine (TMEi)places the decrypted contents of the memory location at the physicaladdress into cache, and the CPU of the key domain-capable servercomputes a hash value, a hash value, such as an SHA2/3 hash value, byhashing the decrypted contents in the cache. Control proceeds to “ReturnHash Value for Memory Content” block 2050, where the hash value isreturned to the issuer of the HashKD command. The issuer of the HashKDinstruction can then determine whether to switch to the verified keydomain.

FIG. 21 is a diagram showing switching between key domains in accordancewith one embodiment of the invention. A switch to a new key domain isinitiated by a memory manager 2140 of a key domain-capable server toswitch from one key domain to another. A switch to a new key domain maybe initiated, for example, in response to a new consumer request forservices received by the key domain-capable server. Having previouslyprovided a domain manager image to the consumer, the memory manager 2140obtains a fixed-up version of the domain manager image (e.g., VMMlet2122) containing memory position-dependent address information such asentry point address 2123 that the consumer has provided via unencrypted(k-bit disabled) memory 2112. Memory manager 2140 issues a Switch KeyDomain (SwitchKD) command to a CPU of hardware 2110, which causes domainmanager image (VMMlet) 2122 to execute beginning at entry point address2123 in the memory of the key domain-capable server, therebyestablishing key domain 2150.

In one embodiment, the consumer calculates an HMAC value for an expectedprocessor state prior to entering a new key domain. The HMAC value forthe expected processor state includes expected values for instructionpointers; stack pointers; control registers (such as control registers0, 3, and 4); and special descriptor table registers, such as GDTR,LDTR, any MSRs that may pertain to the correct execution of theencrypted domain launch image containing the domain manager image, andIDTR. For example, this HMAC value will ensure proper execution within akey domain (i.e., that interrupts are turned off) or else the new keydomain is not entered and no switch between key domains occurs.

Execution of a domain manager (VMMlet) inside a new key domain may beaccomplished using a Switch Key Domain (SwitchKD) instruction. This CPUinstruction determines an HMAC value using the key domain key tovalidate the processor's current processor state on entry. For example,a hash function may be calculated from the same information as used tocalculate the HMAC value for the expected processor state, includinginstruction pointers, stack pointers, control registers, and specialdescriptor table registers. If the calculated HMAC value of the expectedprocessor state does not match a hash value of the CPU's currentprocessor state upon entry, the Switch Key Domain instruction will fail.The key domain selector will remain unchanged, and execution of thedomain manager (VMMlet) will not switch to a new key domain.

In another embodiment, control flow transfer into a new key domainterminates on an End Branch Key Domain (ENDBRANCHKD) instruction. Theonly way to change control flow into a new key domain from another keydomain is to enter the new key domain at an entry point where the nextinstruction to be executed is the End Branch Key Domain instruction.This requirement for changing key domains assures the consumer thatcontrol flow transfers go through an expected entry point.

After correct execution of the Switch Key Domain (SwitchKD) instruction,the domain manager (VMMlet) is now measured and running correctly withinthe key domain. All other functionality is provided by software to loadthe rest of the consumer's domain (VM) image, to perform secure storage,communications, paging (e.g., to page out, the consumer's domain (VM)image needs to go through the domain manager (VMMlet)), migration,Input/Output (I/O), etc.

FIG. 22 is a diagram showing messages between components of a cloudservices environment while executing inside a key domain in accordancewith one embodiment of the invention. In one embodiment, the consumercalculates a hash message authentication code (HMAC) value for anexpected processor state prior to entering a new key domain. The HMACvalue for the expected processor state includes expected values forinstruction pointers; stack pointers; control registers (such as controlregisters 0, 3, and 4); and special descriptor table registers, such asGDTR, LDTR, any relevant MSRs, and IDTR. For example, this HMAC valuewill ensure that the processor state is such that proper execution ofthe domain manager (VMMlet) occurs within a key domain (i.e., thatinterrupts are turned off).

In the next communication, the cloud services provider software, such asa memory manager 2240 on a key domain-capable server, issues a Switch KDcommand to cause the CPU 2211 of the key domain-capable server to switchkey domains. The CPU 2211 sets the key domain selector and checks thatthe expected processor state HMAC value matches an HMAC value calculatedfor the current CPU state. If the HMAC values match, the key domain isswitched, the instruction pipeline is flushed, the translationlook-aside buffer (TLB) address space identifier (ASID) tag is changedfor the key domain identifier, and the domain manager (VMMlet) executesin the new key domain. While executing in the new key domain with thek-bit enabled, memory locations of the key domain are accessed using anaddress set to the key domain selector value. While executing in the newkey domain, the memory encryption engine (TMEi) 2215 can read and writekey domain encrypted data from memory 2212 and check and/or update theintegrity check values (ICVs) for the encrypted data. If the ICV valuesare consistent with the encrypted data, the encrypted data is decryptedinto cache 2213 for the address and key domain selector.

FIG. 23 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a Switch Key Domain operation inaccordance with one embodiment of the invention. At “Receive Switch KeyDomain Command with Input Parameters of Key Domain Identifier, CPUState, and Expected HMAC Value” block 2310, a Switch Key Domain commandis received by the CPU. The input parameters of the Switch Key Domaincommand include the key domain identifier to which to switch, theexpected CPU state to switch to the new key domain, and the ExpectedHMAC value for the processor state. Control proceeds to “Does ExpectedHMAC Value Match CPU State?” decision point 2320. At decision point2320, a determination is made whether the current CPU state and/or theproposed CPU state specified as a parameter to the SwitchKD instructionmatches an expected HMAC value. Some CPU state information, such as theinstruction pointer, is state that is set as a parameter by the SwitchKDinstruction. If the HMAC also matches the Instruction Pointer parameter,then SwitchKD will set the instruction pointer register in the CPUaccordingly, resuming in the new key domain starting execution at thatinstruction location. Alternatively, all CPU state values may beparameters to SwitchKD, meaning that SwitchKD will populate all theregister states to the input parameters if the HMAC matches thatproposed input state. At decision point 2320, if the Expected HMAC valuefor the processor state does not match an HMAC value calculated for thecurrent CPU state or proposed CPU state specified as parameters to theSwitchKD instruction, the key domain is not switched and an error isreturned to the issuer of the Switch Key Domain command in “Return Error(Did Not Switch Key Domain)” block 2330.

At “Does Expected HMAC Value Match CPU State?” decision point 2320, ifthe expected HMAC value for the processor state matches an HMAC valuecalculated for the current CPU state, control proceeds to “Switch to NewKey Domain” block 2340. At “Switch to New Key Domain” block 2340, theCPU pipeline is flushed, and either the address space identifier (ASID)tag for translation look-aside buffers (TLBs) is set to the new keydomain identifier or the TLBs are flushed. The current key domain is setas the key domain identifier, and CPU registers are set to match the CPUstate input parameter values. Control then proceeds to “Branch toExecute Instruction at Location Indicated by CPU State's InstructionPointer” block 2350. At block 2350, the CPU of the key domain-capableserver branches to execute an instruction at the location indicated bythe CPU state's instruction pointer as provided as an input parameter tothe SwitchKD instruction. Upon completing execution of the SwitchKDinstruction, the domain manager (VMMlet) is operating within the new keydomain.

FIG. 24 is a flowchart of a method of operation of a CPU of a keydomain-capable server in performing a walk of paging structures inresponse to a page miss in accordance with one embodiment of theinvention. Control begins at “On Page Miss, Processor Walks PagingStructures” block 2410. Upon encountering a page miss (where a page theCPU attempts to read or write is not found within the translationlook-aside buffers), the CPU of the key domain-capable server beginswalking paging structures (such as the OS paging structure 860 describedwith reference to FIG. 9 or the OS paging structure 960 described withreference to FIG. 9). For example, the CPU of the key domain-capableserver may begin by reading control register 3 (CR3) for a pointer tothe base address of the paging structures. Control then proceeds to“Paging Structure Misconfigured?” decision point 2420, where the CPUdetermines whether the paging structure is configured as expected. Forexample, the CPU determines whether a page fault to the operating systemhas occurred, or a VMExit to the domain manager (VMMlet) has occurred.These faults are still within the same key domain as the domain (VM)image causing the fault. If the paging structure is not configured asexpected, control proceeds to “Hard Fault, CPU Reports Error” block2430, where the CPU causes a hard fault and reports an error to theprocess that encountered the page miss.

At “Paging Structure Misconfigured?” decision point 2420, if the pagingstructure is configured properly, control proceeds to “Determine ASIDTag Assigned to Current Key Domain” block 2440. The address spaceidentifier (ASID) tag assigned to the current key domain is determined,and control proceeds to “Is K-bit Set?” decision point 2450. If theK-bit of the ASID tag is not set, control proceeds to “Use Address As-Isto Fill TLB with K-bit Off” block 2460. At block 2460, the CPU of thekey domain-capable server causes the translation look-aside buffer (TLB)to be filled with the physical address as it is. Leaving the physicaladdress as-is enables data to be read directly from unencrypted memorywithout using a key domain key.

At “Is K-bit Set?” decision point 2450, if the k-bit of the ASID tag isset, control proceeds to “Get Current Key Domain and Replace UpperPhysical Address Bits with Key Domain Identifier” block 2470. Thecurrent key domain is determined from the internal processor state setby the Switch Key Domain (SwitchKD) instruction, which sets the currentkey domain to the key domain identifier of the new key domain, asdescribed with reference to FIG. 23. Upper bits in the physical addressare replaced with the key domain identifier/selector for the current keydomain, with the k-bit (which is the uppermost bit in one embodiment)enabled. Control then proceeds to “Set Translation Look-Aside Bufferwith Address and ASID Tag” block 2480, where the translation look-asidebuffer is set with the physical address (including key domain selectorand k-bit enabled, or k-bit=1) and ASID tag for the current key domain.

FIG. 25 is a diagram showing growth of a domain manager (VMMlet) inaccordance with one embodiment of the invention. Growth of a domainmanager (VMMlet) may be needed, for example, to include additionalmemory to load a remaining portion of the consumer's VM image after theconsumer's domain launch image has been loaded and the domain manager(VMMlet) is executing. Once a secure domain manager (VMMlet) 2522 withconsumer secret keys 2523 is running in a key domain 2550, the consumercan securely communicate the rest of the consumer's VM image 2532 to thedomain manager (VMMlet) 2522. The rest of the consumer's VM image 2532may include, for example, operating system(s), application(s), scripts,or other code.

A secure communication channel between the consumer and the domainmanager (VMMlet) 2522 can be enabled by a Transport LayerSecurity/Secure Sockets Layer (TLS/SSL) connection to the consumer'snetwork, using the consumer's secret keys 2523 of the original encryptedDomain launch image given to the cloud services provider. In otherwords, if the original encrypted domain launch image had an operatingsystem with an OpenSSL stack above the domain manager (VMMlet), and theconsumer's secret keys, that OpenSSL software stack can be executed toretrieve the rest of the consumer's VM image 2532 from the consumer'snetwork.

An operating system running above the domain manager (VMMlet) 2522 maysupport full volume storage encryption, so that the operating system cansecurely page in encrypted pages, files, etc. from k-bit off (shared)channels, where the memory manager 2540 acts as an intermediary. Oncethe original encrypted domain launch image is loaded into memory and isexecuting, domain manager (VMMlet) 2522 may allow other software, suchas the operating system, to page in additional information from theconsumer using any secure method that is desired.

The addition of memory pages for the rest of the consumer's VM image2532 may cause the domain manager (VMMlet) 2522 to need an additionalallocation of memory. In one embodiment, a domain manager (VMMlet) 2522can grow by requesting more memory from the memory manager 2540. Thememory manager 2540 can allocate additional memory to the domain manager(VMMlet) 2522, as shown by “Allocate Memory” action 2501. Thisadditional memory enables the consumer to perform a write-onlyoperation, such as a non-temporal move (MOVNT) operation (a non-cachedwrite combining operation for writing to memory without first readingthe memory), to write additional pages in the domain/VM workload imagefrom the consumer or consumer-authorized third parties. For example, theconsumer can provide the rest of a VM image 2532, including operatingsystem(s), application(s), scripts, or other code, via a secureconnection to the domain (VMMlet) 2522.

FIG. 26 is a diagram showing messages between components of a cloudservices environment to grow a domain manager (VMMlet) in accordancewith one embodiment of the invention. The consumer 2601 sends the restof the VM image to cloud services provider software, such as a memorymanager 2640 of a key domain-capable server. In one embodiment, the restof the VM image is communicated from the consumer to the running domainmanager (VMMlet) via a Transport Layer Security (TLS)/Secure SocketsLayer (SSL) communication session from the consumer using the consumer'ssecret keys (such as keys 2523 of FIG. 25) to the running domain image'sTLS stack.

As described above with reference to FIG. 25, the consumer's secret keysare included as part of the consumer's encrypted domain launch imagegiven to the cloud services provider. At the point in time representedby FIG. 26, the consumer's VM is securely running and self-sufficient,running any software the consumer provided on top of the VMMlet (similarto an operating system running on top of a VMM). Data packets are sentfrom the consumer 2601 to the running domain manager (VMMlet) via thememory manager 2640 through shared, unencrypted memory (i.e., memory2612 with the k-bit disabled). These data packets may include a streamof software encrypted data that the consumer's software running withinthe consumer's VM on top of the running domain manager (VMMlet) candecrypt and verify.

The cloud provider software may send, on behalf of the consumer, thedata for the rest of the VM image through shared, unencrypted memory(i.e., memory 2612 with the k-bit disabled) via the CPU 2611 and memoryencryption engine (TMEi) 2615. The data for the rest of the VM image isshown as flowing from CPU 2611 through memory encryption engine (TMEi)2615 to memory 2612, as illustrated by the two “Write Data” actions.When data for the rest of the VM image is provided to the cloud servicesprovider, the cloud services provider software may cause the CPU 2611 toexecute a Switch Key Domain (SwitchKD) instruction to switch to the keydomain for the consumer's running domain manager (VMMlet).Alternatively, the CPU 2611 may provide control to the consumer'srunning domain manager (VMMlet) that is running on another thread oranother CPU. These actions by CPU 2611 are shown by the “SwitchKD (Or KDRunning on Another CPU/Thread)” action of FIG. 26.

The running domain manager (VMMlet) copies the data (including the restof the VM image) from unencrypted memory to encrypted memory that ispart of the consumer VM's key domain. As shown by the “Read Data”action, the memory encryption engine (TMEi) 2615 reads data from theunencrypted memory. In the “Read Data for Address with Shared !k KDSelector” action, the domain manager (VMMlet) running on the CPU 2611reads the data from an unencrypted memory location identified by the keydomain address selector that was provided with the data in theunencrypted memory.

The running domain manager (VMMlet) may process the data, decrypting thedata in software, performing integrity checks, and so on. For example,the running domain manager (VMMlet) may request the memory encryptionengine (TMEi) 2615 to write encrypted data to a memory address with akey domain address selector that was provided in the unencrypted memory.As shown in “k-bit On Memory Accesses have Address Set to KD Selector;Use MOVNT Instruction on First Write to New Memory Address” action ofFIG. 26, CPU 2611 writes encrypted data and associated integrity checkvalues to an address specified in the key domain identifier/selectorinto memory 2612 (with k-bit enabled, indicating that the data isencrypted with the key domain key prior to writing the data to memory2612).

Writing data to a memory address establishes an “owner” of the memorylocation. When switching between key domains, the owner of a memorylocation changes from the owner of one key domain to the owner ofanother key domain. When the key domain changes, the corresponding keydomain key for encrypting data stored in the memory locations belongingto the key domain changes accordingly.

When data are read from a memory location belonging to a key domain, the“current” key domain key is used. After a switch key domain instruction,a new “current” key domain key must be established. As described above,the “current” key domain key is established upon writing data to thememory location, thereby establishing a new owner of the memorylocation. When data is read from a memory location, the read operationwill use the “current” key domain key. If the data is read from thememory location before the owner of the new key domain has written tothe memory location, the read operation will use the current key domainkey, which has not yet been changed to reflect the new owner of the keydomain. The read operation will be unsuccessful because the currentintegrity check value for the memory location will belong to theprevious key domain. The integrity check will fail because the readercannot read data belonging to another key domain.

To alleviate this problem, when a new key domain is established, theowner of the new key domain writes new data to the memory locationswithin the key domain without attempting to read the memory locationsfirst. On the write operation, a new integrity check value (ICV) will becalculated for the new key domain; thus, the owner of the new key domainwill now own that memory content (and be able to read and write thatmemory location without integrity failures).

In one embodiment, a MOVNT instruction is used to perform the firstwrite operation to a new memory address. The memory encryption engine(TMEi) writes the encrypted data and ICVs to memory, thereby completingthe process of copying the data from unencrypted memory to encryptedmemory that is part of the consumer VM's key domain.

The MOVNT instruction is a write-combining operation, which means thatthe MOVNT instruction does not require a read operation to fetch thememory contents because the current contents are not needed. The MOVNTinstruction may bypass the cache and write directly to memory. As analternative to using the MOVNT instruction, the running domain manager(VMMlet) may use uncached write operations to copy the data fromunencrypted memory to encrypted memory that is part of the consumer VM'skey domain. By writing to a memory address without first reading datafrom that memory address, a new integrity check value (ICV) is created(via write for ownership).

Once a full consumer domain (VM) image is installed, the domain (VM)will function as a normal VM, using secret keys to establish securecommunications to the consumer, consumer-authorized third parties, andother authorized VMs. Secure storage is achieved by encrypting fullvolumes and/or files in file system with consumer secret keys. Securecommunications are achieved via IPSec/TLS and consumer secret keys.Attestation is achieved using consumer's secret keys (PKI, etc.). Securemigration of domains (VMs) between servers in the cloud servicesprovider's infrastructure can be achieved by using the consumer's secretkeys to encrypt VM image pages (and compute integrity check values forthose VM image pages). The VM image pages can then be sent to otherservers in the cloud services provider's infrastructure, along with theconsumer's domain manager (VMMlet) pages, to securely migrate theconsumer's VM image from one server to another.

FIG. 27 is a diagram showing messages between components of a cloudservices provider's environment for a running domain manager (VMMlet) torequest more memory pages from a cloud services provider's memorymanager software. In this environment, multiple CPUs simultaneouslyshare memory 2712. Cloud provider software (e.g., memory manager) 2740runs on a first CPU1 of a key domain-capable server. A virtual machine2730 runs on a second CPU2 of the key domain-capable server. VM 2730requests additional memory, as shown in the “Ask for More Memory” actionbetween VM 2730 and memory manager 2740. (Actually, the operating systemthat is part of VM 2730 running on top of the VMMlet may require morememory. The operating system may cause a VMExit to exit VM 2730, therebyinvoking the host VMMlet, which then requests more memory from the cloudprovider's memory manager 2740.) The domain manager (VMMlet) running onCPU2 sends the write request on behalf of the consumer's VM 2730 viashared unencrypted memory (with k-bit disabled), as shown by the “!kRequest Message” action between VM 2730 and memory encryption engine(TMEi) 2715. The memory encryption engine (TMEi) 2715 passes through thememory request to shared memory 2712 without processing the request,because the k-bit is disabled. Memory manager 2740 on CPU1 reads therequest for additional memory written by VM 2730 on CPU2, as indicatedby the dotted line from memory 2712 to memory manager 2740 on CPU1. Thedomain image running on CPU2 (i.e., VM 2730) waits for a response, suchas an interrupt (IPI), as shown in “Wait for Response, e.g. Interrupt(IPI)” action of VM 2730. When free memory locations are provided by thecloud services provider's memory manager software 2740, the memorymanager 2740 on CPU1 writes response data to shared memory 2712 (withk-bit disabled), as shown by the dotted line from memory manager 2740 onCPU1 to shared memory 2712. VM 2730 on CPU2 reads the response data fromshared memory 2712 (with k-bit disabled), as shown in the “Read ResponseData” action between shared memory 2712 and memory encryption engine(TMEi) 2715. The memory encryption engine (TMEi) 2715 passes theresponse data through to VM 2730 on CPU2, as shown by the “!k ResponseMessage” action from TMEi 2715 to VM 2730 on CPU2. The VM 2730 updatespage tables in VM's key domain, as shown by the “Update Page Tables inVM's Key Domain” action between VM 2730 and memory encryption engine(TMEi) 2715. The memory encryption engine (TMEi) 2715 writes theencrypted data and integrity check value to memory 2712 (with k-bitenabled), as shown by the “Write Encrypted Data and ICV” action betweenmemory encryption engine (TMEi) 2715 and shared memory 2712. The domainmanager (VMMlet) hosting VM 2730 causes CPU2 to execute a MOVNTinstruction to write data to the newly-allocated memory in VM's keydomain, as indicated by the “MOVNT to Newly Allocated Memory in VM's KeyDomain” action between VM 2730 and memory encryption engine (TMEi) 2715.In response, the memory encryption engine (TMEi) 2715 writes theencrypted data and ICV to the newly-allocated encrypted memory.

FIG. 28 is a diagram showing messages between components of a cloudservices environment showing requesting additional memory pages whilescheduling VMs on a single CPU. The cloud services provider's memorymanager 2840 decides the scheduling scheme with regard to which VM iscurrently executing. Domain managers (VMMlets) running on the cloudservices provider's CPU/core receive timer events and yield time toother VMs based on the memory manager command queue (k-bit disabledshared memory region). A Switch Key Domain (SwitchKD) operation is usedto switch to another domain manager (VMMlet).

Referring to FIG. 28, the VM 2830 prepares a message requestingadditional memory from the memory manager 2840 in the “Prepare Messageto Memory Manager” action and places the message in cache 2813 to beread into unencrypted (k-bit disabled) memory 2812 in the “!k Request inCache” action between VM 2830 and memory encryption engine (TMEi) 2815.The memory encryption engine (TMEi) 2815 writes the request data tomemory 2812 (with k-bit disabled) in the “Write Request Data” actionbetween memory encryption engine (TMEi) 2815 and memory 2812. The VM2830 saves the processor state in the “Save Processor State” action andplaces the saved VM processor state in cache 2813 in “Save State in VM'sKD k-bit On”. The VM's saved state processor state is written to theVM's key domain encrypted (k-bit enabled) memory. The memory encryptionengine (TMEi) 2815 writes the saved VM processor state as encrypted datawith ICVs to the VM's key domain encrypted (k-bit enabled) memory 2812in the “Write Encrypted Data and ICV” action between memory encryptionengine (TMEi) 2815 and memory 2812. Saving the VM's processor stateenables the domain manager (VMMlet) to resume execution of the VM laterusing the saved processor state. In one embodiment, the domain manager(VMMlet) clears registers after the processor state has been saved sothat the VM's secrets are not available after a switch to another keydomain.

To enable the memory manager 2840 to allocate additional memory for VM2830, the key domain is switched from the VM 2830 key domain to thememory manager 2840 key domain. In the “SwitchKD to Provider” actionbetween VM 2830 and memory manager 2840, VM 2830 sends a Switch KeyDomain instruction to the cloud services provider. Memory manager 2840begins restoration of the processor state associated with the memorymanager 2840 key domain in the “Restore Processor State” action.Encrypted data and integrity check values for the memory manager 2830key domain are read from memory 2812 in the “Read Encrypted Data andICV” action between memory 2812 and memory encryption engine (TMEi)2815. Memory encryption engine (TMEi) 2815 decrypts the data for thecurrent key domain and sends the decrypted data to cache (assuming thatthe corresponding ICV values are correct). Memory manager 2840 restoresthe processor state from the memory manager 2840 key domain in the“Restore State from Memory Manager's KD” action between memoryencryption engine (TMEi) 2815 and memory manager 2840.

In the “Read Request Data” action between memory 2812 and memoryencryption engine (TMEi) 2815, the memory encryption engine (TMEi) 2815reads the additional memory request data from the k-bit disabled commandqueue of memory 2812 into cache 2813. In the “!k Data Request in Cache”action between memory encryption engine (TMEi) 2815 and memory manager2840, the memory manager 2840 reads the additional memory data requestsaved in cache 2813.

In “!k Provide Free Memory Locations” action between memory manager 2840and memory encryption engine (TMEi) 2815, memory manager 2840 sends themessage via the unencrypted (k-bit disabled) memory command queue toprovide free memory locations to the memory encryption engine (TMEi)2815. In “Write Response Data” action between memory encryption engine(TMEi) 2815 and memory 2812, memory encryption engine (TMEi) 2815 writesresponse data, including addresses of the free memory locationsallocated for VM 2830, to memory 2812. Having completed the allocationof additional memory in response to the request from VM 2830, memorymanagement engine 2840 saves the current processor state in thecontroller's key domain in the “Save State in Memory Manager's KD”action. In the “Write Encrypted Data and ICV” action between memoryencryption engine (TMEi) 2815 and memory 2812, memory encryption engine(TMEi) 2815 writes the encrypted data (saved processor state) andintegrity check values to the memory manager 2840 key domain in memory2812. Memory manager 2840 then executes a Switch Key Domain (SwitchKD)operation to switch back to the VM's key domain.

In response to switching to the VM 2830 key domain, VM 2830 begins torestore the VM 2830 saved processor state in the “Restore ProcessorState” action. Memory encryption engine (TMEi) 2815 reads encrypted data(including the processor state) and integrity check values for the VM2830 key domain in the “Read Encrypted Data and ICV” action betweenmemory encryption engine (TMEi) 2815 and memory 2812. In the “RestoreState from VM's KD” action between memory encryption engine (TMEi) 2815and VM 2830, the VM 2830 restores the saved processor state from its VM2830 key domain.

At the time that VM 2830 was previously executing prior to switching tothe memory manager 2840 key domain, VM 2830 had requested additionalmemory. In the “Read Response Data” action between memory encryptionengine (TMEi) 2815 and memory 2812, memory encryption engine (TMEi) 2815reads response data for the request for additional memory and providesthe response data in cache 2813 for the VM 2830. The VM 2830 updatespage tables in the VM 2830 key domain to reflect the newly-allocatedmemory locations in the “Update Page Tables in VM's KD” action betweenVM 2830 and memory encryption engine (TMEi) 2815. In the “WriteEncrypted Data and ICV” action between memory encryption engine (TMEi)2815 and memory 2812, the memory encryption engine (TMEi) 2815 writesencrypted data (the updated page tables) and integrity check values tomemory 2812.

To establish ownership of the newly-allocated memory, the VM 2830 thenperforms a MOVNT operation (or other write operation that does not readcontents of the memory location before writing to the memory location)to the newly-allocated memory in the VM's key domain in the “MOVNT toNewly Allocated Memory in VM's KD” action between VM 2830 and memoryencryption engine (TMEi) 2815. The MOVNT operation establishes VM 2830as owner of the newly-allocated memory. In the “Write Encrypted Data andICV” action between memory encryption engine (TMEi) 2815 and memory2812, the memory encryption engine (TMEi) 2815 writes the encrypted dataand ICV to memory 2812. As part of this write operation, memoryencryption engine (TMEi) 2815 calculates new integrity check values forthe newly-allocated memory in the VM 2830 key domain. The new integritycheck values will ensure that the VM 2830 key domain key can be used todecrypt contents of the newly-allocated memory.

FIG. 29 is a diagram showing a running domain manager (VMMlet) 2922.Prior to running the domain manager (VMMlet) 2922, the memory manager2940 of a key domain-capable server verifies a hash of the processorstate before executing the domain launch image for the domain manager(VMMlet). Once the processor state is verified, the domain launch imageis executed to run the domain manager (VMMlet).

The memory manager 2940 issues commands to the running domain manager(VMMlet) 2922 via unencrypted (k-bit disabled) memory 2912. Similarly,hardware 2910 of the key domain-capable server issues Direct MemoryAccess (DMA) requests to the running domain manager (VMMlet) viaunencrypted (k-bit disabled) memory 2912. In response to receiving thesecommands or DMA requests, domain manager (VMMlet) 2922 interacts withkey domain-capable server hardware 2910 to set and/or access registervalues, process interrupts, perform VM entry and exit, and so on.

Memory manager 2940 decides the scheduling scheme with regard to whichVM is currently executing; in FIG. 29, the currently executing VM is VM22930 and the associated key domain is key domain 2950. A Switch KeyDomain (SwitchKD) operation is used to switch to another domain (VM).

Dynamic entry points can be created locally within a VM once the dynamicportion of the VM image (i.e., the remaining portion of the VM imagethat is not included in the domain launch image) is loaded. For example,in response to a Switch Key Domain (SwitchKD) instruction, a newkeyed-hash message authentication code (HMAC) may be calculated based onthe key domain key.

Interrupts and VM exit instructions are delivered to the current domainmanager (VMMlet) running on the CPU/core of the key domain-capableserver. The running domain manager (VMMlet) decides whether aninterrupt/asynchronous event is intended for the currently runningdomain manager (VMMlet) or for another domain manager (VMMlet). If theinterrupt/asynchronous event is intended for another domain manager(VMMlet), the domain manager (VMMlet) will schedule the correct domainmanager (VMMlet) or notify the memory manager.

With regard to resource management, paging is accomplished throughsoftware rather than via a hardware paging mechanism. The domain manager(VMMlet) encrypts pages (including integrity metadata) in software(e.g., using Intel® AES new instructions (AESNI) for accelerating AESencryption), updates page tables and extended page tables, and sendsencrypted pages through k-bit disabled memory for storage or migration.

With regard to input/output operations, either direct assignment orvirtualized device models may be used. The k-bit designated unencryptedmemory regions used for DMA and memory mapped input/output (MMIO) arenon-encrypted. While direct assignment DMA is possible, MMIO/PCIe devicespace must be k-bit disabled (unencrypted) memory. The processor mustassure that key domain transactions are only allowed to dynamic randomaccess memory (DRAM) and not to device space.

FIG. 30 is a diagram showing multiple virtual machines within a keydomain managed by a domain manager (VMMlet), as well as a second keydomain managed by an another type of domain manager (OSlet).

Because the domain manager (VMMlet) is a fully functional VMM, thedomain manager (VMMlet) can host multiple guest operating systems(OS)s/VMs within its key domain. VM2 3033 and VM3 3034 are shown asrunning within key domain KD1 3050 ₂ of domain manager (VMMlet) 3022,and process 3031 is shown as running within key domain KD2 3050 ₁ ofOSlet 3060. As is the case when switching between domain managers(VMMlets), a Switch Key Domain (SwitchKD) command is issued by memorymanager 3040 to switch between domain types; i.e., a SwitchKD command isissued to switch between a domain manager (VMMlet) and a domain manager(OSlet).

Consumers want to be assured that public cloud services providers cannotaccess their workloads, even if served by a government issued warrant todo so. With the features provided by the secure public cloud environmentdescribed herein, a cloud services provider, on-site administrator ortechnician cannot access secure VM data, even if the VMM itself isrewritten (because the consumer can measure their entire TCB).

The above embodiments have been described with regard to a domainmanager (VMMlet) that manages virtual machines, although the inventionis not so limited. The same model can support containers; although thereis no corresponding VMM, the OS kernel is the equivalent. Each containerimage in each key domain will have cooperating kernel components(referred to herein as a domain manager (OSlet)) measured by theprovider. A domain manager (OSlet) responds to memory manager commands,interrupts, scheduling, resource management, etc., in a similar manneras the domain manager (VMMlet).

FIGS. 31A and 31B illustrate determination of integrity line locationand slot from a physical memory address as a hardware function of amemory encryption engine. Unused address bits are passed through cache,but they are unused because they correspond to unpopulated physicalmemory. The unused bits are used to encode key domain (KD) selectorinformation in the address. Different keys can be selected based onunused address bits for memory position-dependent encryption of datalines and corresponding integrity check values.

Physical memory address 3100 may be used to determine a key or a tweak,discussed above, and/or an integrity check line 3112 and a slot 3114(3114 a-3114 h) for an integrity value associated with a data line 3116(3116 a-3116 h) according to an embodiment. The physical memory address3100 may include a plurality of address bits that may be partitionedinto a plurality of sections. The sections of the data physical memoryaddress 3100 may be identified as data line bytes 3102, a data linephysical address 3104 (actual location in memory of the data) whichincludes an integrity line slot selector 3110 and integrity line index3108 (e.g., an offset to the integrity check line 3112), and unusedaddress bits 3106 (e.g., alias bits) that alias to the same physicalmemory. The unused address bits 3106 passed through cache, but unusedbecause unpopulated external memory, may be used to encoded aliasinformation in the data physical memory address 3100. Accordingly,different keys can be selected based on unused address bits. Forexample, the encryption technique XTS (XEX-based (XOR-encrypt-XOR-based)tweaked codebook mode with ciphertext stealing) may use the alias bitsfor a tweak for the same physical memory location, where differentaddress aliases may result in different ciphertext even if the data isthe same

A memory selector (e.g., memory encryption engine 415 of FIG. 4) mayread the data line physical address 3104 and identify the correspondingintegrity line address 3112 and integrity line slot (e.g., 3114 a-3114h) to use to validate the data line bytes 3102 and/or the validity of anintegrity check value stored in the integrity line slot (e.g., 3114a-3114 h). The value in the alias bits 3106 may be stored in theintegrity line slot (e.g., 3114 a-3114 h) as ciphertext used to decryptthe data line bytes, and/or compared with a value read from theintegrity line slot (e.g., 3114 a-3114 h) identified by the alias bits3106 to validate the data line bytes.

Notably, not all bits of memory may be addressable since, for example,the actual memory deployed in a computing platform may be substantiallyless than a maximum amount of possible memory for which a maximum amountof address space is provisioned. For example, not all 64-bits (of a64-bit system) of physical memory are addressable (e.g., occupied withsufficient DIMM's). Thus, otherwise unused bits of the physical memoryaddress 3100 may be used to determine, for example, which key and/ortweak is to be used when encrypting and/or decrypting memory for aparticular data line.

The key domain and/or the tweak domain for the physical memory address3100 may be any size. In the illustrated example, a value selector mayuse the unused address bits 3106 to derive a key and/or a tweak for thesame physical memory address 3100. For example, a software valueselector may select from among 16 keys (and/or 16 tweaks) defined byfour most significant bits of the unused address bits 3106. In oneexample, setting the first bit to zero (0000) or to one (0001) may beused to derive the key tweak (e.g., if set bit to 1, encrypt with 1, ifset to 0, encrypt with 0) or the tweak (e.g., if set bit to 1, use 1 inaddress for tweak, if set to 0, use 0 in address for tweak, etc.). Thus,different keys and/or tweaks may be used. In this case, a firstintegrity check will fail when data is decrypted with a wrong key and/ora wrong tweak, and/or a second integrity check will fail when anintegrity value is checked against improperly decrypted data.

Additionally, an integrity check line and/or a slot may be determinedand selected from the physical memory address 3100. For example, anintegrity line selector may select the integrity check line from theintegrity line index section 3108 of the physical memory address 3100,and/or the slot selector may select the slot from the integrity lineslot selector section 3110 of the physical memory address 3100.

As shown in FIG. 31B, data lines may be stored in data memory addressspace and integrity values (e.g., an ICV, a copy, etc.) may be stored inintegrity data address space. For example, the data lines in the datamemory address space begin at address 0, and the integrity check linesin the integrity data memory address space begin 1000 cache lines awayfrom the data lines at address 1000.

While various strategies may be implemented to map between each of thedata lines and each of the integrity check lines (and/or each of theslots thereof) in embodiments, using a data line address may be anefficient approach to determine and select an appropriate integritycheck line and an appropriate slot. For example, no lookup table may beneeded to determine the appropriate integrity check line and/or the slotfor an integrity value. In this regard, a value defined by intermediatebits of each of the data lines 3116 a-3116 h may map to the integritycheck line 3112, indicated by the arrows from the data lines 3116 a-3116h with the addresses 0-7 to the integrity check line 3112, and a valuedefined by least significant bits of each of the data lines 3116 a-3116h may map to the appropriate slot 3114 a-3114 h that is to accommodateparticular integrity values for each of the data lines 3116 a-3116 h,indicated by the location of the arrows.

Generally, selection of an appropriate integrity check line and anappropriate slot may be based on a function, such as(D−Dstart)/8+Istart, wherein the address Dstart of the start of the datamemory region is subtracted from the address D of the data line that isto be accessed, wherein Istart is the start of the integrity valuememory address space, and wherein the integer division by 8 may be doneby shifting the address offset right by 3 (or choosing top bits minusthe first 3 bits). Moreover, once the appropriate integrity check lineis fetched, the offset for the appropriate slot may be determined by(D−Dstart)%8, wherein the modulo operation may select the leastsignificant 3 bits of the address. It should be understood that while 3bits may be used to select from 8 slots on an integrity check line, theintegrity check lines may be different in size (e.g., half the size),such that 4 bits may be used to select from 16 slots per integrity checkline to save on integrity value overhead, and so on.

The intermediate bits and/or the least significant bits may also be usedas an index to an array of assigned locations stored in aprivileged/secure memory location to identify the mappings. There mayalso be an implied mapping, wherein the first slot 3114 a of the firstintegrity check line 3112 may be automatically selected for the dataline 3116 a having address 0, the second slot 3114 b of the firstintegrity check line 3112 may be automatically selected for the dataline 3116 b having address 1, and so on. Any functions, mappings, and/orassignments may be used, such that the data lines 3116 a-3116 h with theaddresses 0-7 may be mapped to anywhere in the integrity data addressspace, may be mapped to anywhere within the integrity check line 3112,and so forth.

A secure public cloud environment is achieved without additionalperformance overhead beyond a memory encryption engine. In oneembodiment, the memory encryption engine is provided as a MemoryEncryption Engine (MEE), as described in U.S. Pat. No. 8,819,455,“Parallelized Counter Tree Walk for Low Overhead Memory ReplayProtection.” In another embodiment, a memory encryption engine withintegrity is provided, as described in U.S. Pat. No. 9,213,653, “MemoryIntegrity.” In one implementation of the secure public cloud environmentwith a Total Memory Encryption with Integrity (TMEi) engine, the TMEiengine operates with only 3% overhead. Finally, only minimal hardwarechanges are used to ensure a secure public cloud environment, leveraginga memory encryption engine such as the TMEi engine and pushing most ofthe complexity to software (specifically the VMM). These features allowfor simple verification of the VMM and quick time to market for hardwaresupporting the secure public cloud environment functionality.

FIG. 32 is a diagram showing a system in accordance with one embodiment.As seen, system 3200 may be a smartphone or other wireless communicatoror any other IoT device. A baseband processor 3205 is configured toperform various signal processing with regard to communication signalsto be transmitted from or received by the system. In turn, basebandprocessor 3205 is coupled to an application processor 3210, which may bea main CPU of the system to execute an OS and other system software, inaddition to user applications such as many well-known social media andmultimedia apps. Application processor 3210 may further be configured toperform a variety of other computing operations for the device.

In turn, application processor 3210 can couple to a userinterface/display 3220, e.g., a touch screen display. In addition,application processor 3210 may couple to a memory system including anon-volatile memory, namely a flash memory 3230 and a system memory,namely a DRAM 3235. In some embodiments, flash memory 3230 may include asecure portion 3232 in which keys, other secrets and other sensitiveinformation may be stored and operated. One or more of these storagesmay store information for providing the secure public cloud describedherein. As further seen, application processor 3210 also couples to acapture device 3245 such as one or more image capture devices that canrecord video and/or still images.

Still referring to FIG. 32, a universal integrated circuit card (UICC)3240 comprises a subscriber identity module, which in some embodimentsincludes a secure storage 3242 to store secure identity information.System 3200 may further include a security processor 3250 that may thatmay implement a trusted execution environment (TEE), and which maycouple to application processor 3210. Furthermore, application processor3210 may implement a secure mode of operation, such as Intel® SoftwareGuard Extensions (SGX) to a given instruction set architecture, andcircuitry for hosting of a trusted execution environment (TEE). Securityprocessor 3250 and/or application processor 3210 may be configured toparticipate in the operations in support of providing a secure publiccloud as described herein. A plurality of sensors 3225, including one ormore multi-axis accelerometers may couple to application processor 3210to enable input of a variety of sensed information such as motion andother environmental information. In addition, one or more authenticationdevices 3295 may be used to receive, e.g., user biometric input for usein authentication operations.

As further illustrated, a near field communication (NFC) contactlessinterface 3260 is provided that communicates in a NFC near field via anNFC antenna 3265. While separate antennae are shown in FIG. 4,understand that in some implementations one antenna or a different setof antennae may be provided to enable various type of wirelessfunctionality. A power management integrated circuit (PMIC) 3215 couplesto application processor 3210 to perform platform level powermanagement. To this end, PMIC 3215 may issue power management requeststo application processor 3210 to enter certain low power states asdesired. Furthermore, based on platform constraints, PMIC 3215 may alsocontrol the power level of other components of system 3200.

To enable communications to be transmitted and received such as in oneor more IoT networks, various circuitry may be coupled between basebandprocessor 3205 and an antenna 3290. Specifically, a radio frequency (RF)transceiver 3270 and a wireless local area network (WLAN) transceiver3275 may be present. In general, RF transceiver 3270 may be used toreceive and transmit wireless data and calls according to a givenwireless communication protocol such as 3G or 4G wireless communicationprotocol such as in accordance with a code division multiple access(CDMA), global system for mobile communication (GSM), long termevolution (LTE) or other protocol. In addition a GPS sensor 3280 may bepresent, with location information being provided to security processor3250, which may be used in certain security operations. Other wirelesscommunications such as receipt or transmission of radio signals, e.g.,AM/FM and other signals may also be provided. In addition, via WLANtransceiver 3275, local wireless communications, such as according to aBluetooth™ or IEEE 802.11 standard can also be realized.

Referring now to FIG. 33, shown is a block diagram of a system inaccordance with another embodiment of the invention. As shown in FIG.32, multiprocessor system 3300 can be implemented as a point-to-pointinterconnect system such as a key domain-capable server system. System3300 includes a first processor 3370 and a second processor 3380 coupledvia a point-to-point interconnect 3350. As shown in FIG. 5, each ofprocessors 3370 and 3380 may be multicore processors such as SoCs,including first and second processor cores (i.e., processor cores 3374 aand 3374 b and processor cores 3384 a and 3384 b), although potentiallymany more cores may be present in the processors. In addition,processors 3370 and 3380 each may include a secure engine 3375 and 3385to perform the secure public cloud operations as described herein.

Still referring to FIG. 33, first processor 3370 further includes amemory manager hub (MCH) 3372 and point-to-point (P-P) interfaces 3376and 3378. Similarly, second processor 3380 includes a MCH 3382 and P-Pinterfaces 3386 and 3388. As shown in FIG. 33, MCH's 3372 and 3382couple the processors to respective memories, namely a memory 3332 and amemory 3334, which may be portions of main memory (e.g., a DRAM) locallyattached to the respective processors. First processor 3370 and secondprocessor 3380 may be coupled to a chipset 3390 via P-P interconnects3352 and 3354, respectively. As shown in FIG. 33, chipset 3390 includesP-P interfaces 3394 and 3398.

Furthermore, chipset 3390 includes an interface 3392 to couple chipset3390 with a high performance graphics engine 3338, by a P-P interconnect3339. In turn, chipset 3390 may be coupled to a first bus 3316 via aninterface 3396. As shown in FIG. 33, various input/output (I/O) devices3314 may be coupled to first bus 3316, along with a bus bridge 3318which couples first bus 3316 to a second bus 3320. Various devices maybe coupled to second bus 3320 including, for example, a keyboard/mouse3322, communication devices 3326 and a data storage unit 3328 such as anon-volatile storage or other mass storage device. As seen, data storageunit 3328 may include code 3330, in one embodiment, including code forperforming the secure public cloud operations described herein. Asfurther seen, data storage unit 3328 also includes a trusted storage3329 to store sensitive information to be protected. Further, an audioI/O 3324 may be coupled to second bus 3320.

Embodiments may be used in environments where IoT devices may includewearable devices or other small form factor IoT devices such as anactuator and/or sensor. Referring now to FIG. 34, shown is a blockdiagram of a module 3400 in accordance with another embodiment. In oneparticular implementation, module 3400 may be an Intel® Curie™ modulethat includes multiple components adapted within a single small module.Module 3400 may be configured to participate in the secure public cloudoperations described herein. As seen, module 3400 includes a core 3410(of course, in other embodiments more than one core may be present).Such core may be a relatively low complexity in-order core, such asbased on an Intel Architecture® Quark™ design. In some embodiments, core3410 may implement a trusted execution environment. Core 3410 couples tovarious components including a sensor hub 3420, which may be configuredto interact with a plurality of sensors 3480, such as one or morebiometric, motion environmental or other sensors. A power deliverycircuit 3430 is present, along with a non-volatile storage 3440. In anembodiment, this circuit may include a rechargeable battery and arecharging circuit, which may in one embodiment receive charging powerwirelessly. One or more input/output (TO) interfaces 3450, such as oneor more interfaces compatible with one or more of USB/SPI/I2C/GPIOprotocols, may be present. In addition, a wireless transceiver 3490,which may be a Bluetooth™ low energy or other short-range wirelesstransceiver is present to enable wireless communications as describedherein. Understand that in different implementations an IoT module cantake many other forms that have, in comparison with a typical generalpurpose CPU or a GPU, a small form factor, low power requirements,limited instruction sets, relatively slow computation throughput, or anyof the above.

As described above with reference to FIGS. 1-34, a consumer may providean encrypted domain image to the cloud services provider. In thediscussion of FIGS. 1-34, the consumer's encrypted domain image includescode to be executed as the consumer's workload and associated data. Theconsumer's workload and associated data are described above in thecontext of a consumer virtual machine, and a portion of the codeprovided by the consumer includes a portion of the code for a VMMmanaging the consumer's virtual machine. This portion of the VMM code isdescribed above as a consumer domain manager image, or a “VMMlet.”

In the discussion of FIGS. 1-34, the domain manager (VMMlet) isprivileged code having the ability to create, exit, and resume executionof VMs. These privileges may be referred to as “vmxroot” functionality,and include the ability to perform commands such as a Virtual MachineControl Structure (VMCS) save/restore, General Purpose Register (GPR)save/restore, and/or VMexit/VMresume. Furthermore, the domain manager(VMMlet) controls critical resources such as Interrupt Descriptor Tables(IDT), Advanced Programmable Interrupt Controller (APIC) instructions,and paging data structures such as Page Tables and Extended Page Tables(EPTs). Because the domain manager image described in FIGS. 1-34 hadroot privileges (the VMMlet served as the VMM), the host VMM couldaccess all memory (with its key). No restrictions were placed on thehost VMM's access to the consumer's workload and data.

In contrast to the disclosure described with respect to FIGS. 1-34, thepresent disclosure does not provide root privileges to the consumer'simage. Instead, the consumer's image runs as a guest VM, which can onlyaccess the memory that is mapped and granted permission in the ExtendedPage Tables (EPTs).

The following portions of this application describe techniques thatreduce the encrypted consumer domain image to exclude the domain manager(VMMlet) and remove the need for the cloud services provider to trustconsumer-provided code. The encrypted consumer domain image may includeonly an encrypted consumer domain control structure that is specific tothe consumer's virtual machine. The control structures that normallywould be provided by the host VMM are now also included in the encryptedconsumer domain image provided by the consumer, or an intermediarytrusted by the consumer, to the cloud services provider.

By providing the control structure that sets the consumer's VM processorstate, the consumer retains control of the consumer workload withoutrelying upon the host virtual machine monitor to protect the consumer'sworkload and data. Furthermore, providing the control structure withinthe encrypted memory for which the host VMM does not have access and forwhich the host VMM does not possess the encryption key further protectsthe consumer's workload and data from a compromised host VMM.

In one embodiment, where an agent has direct access to a guest VM'scontrol and/or memory mapping structures, a software policy for mutualprotection of the cloud environment is implemented. Either the agent orthe guest VM that the agent protects can run at a given time, but bothcannot run at the same time. The host VMM protects itself by verifyingthe agent's control structures (VMCS and EPTs, using a VMRead and/orHashKD instruction) prior to launching or resuming the agent to run inthe cloud environment. The software policy implements several hostself-protection rules, such as disallowing a VMCS that can edit itself,disallowing a VMCS that can edit its own EPTs, disallowing overlap inEPTs, and allowing an agent to modify another guest VM's VMCS only whenthe other guest VM is offline (not executing).

An agent protects another guest VM by verifying host requests to modifythe other guest's VMCS or EPTs. An agent protects itself by keeping aseparate VMCS for the guest and keeping a VMCS state for each hardwarethread. An agent also checks EPTs to ensure that guest EPTs do not allowaccess to the agent, and that the guest EPTs do not leak data byspecifying non-encrypted (k-bit off) memory when the data page should beencrypted (k-bit on). In addition, the agent will verify that guestphysical address (GPA) to physical address memory mappings, permissionsbits (R/W/X), memory types, paging hierarchy, and other controlstructure information are correct.

Furthermore, the host VMM and agent can maintain separate copies ofverified control structures. By maintaining a separate copy of verifiedcontrol structures, the host VMM and agent can compare the contents ofthe control structures to ensure they are the same (e.g., using the HashKey Domain (HashKD) instruction to compare the hash values).

FIG. 35 shows a cloud service provider server environment 3500 includinghardware 3510 controlled by a virtual machine monitor (VMM) 3522 of aVMM layer 3520. VMM layer 3520 uses data structures such as a VM controlstructure (VMCS) 3524 and extended page tables (EPTs) 3526 to controlexecution of virtual machines (VMs). The VMCS is a data structure inmemory that exists once for each logical processor for each guest VM,while the guest VM is managed by the host VMM. In a multi-processorsystem, each processor simultaneously executing the guest VM may have aunique VMCS. With every change of the execution context betweendifferent VMs, the VMCS is restored for the current VM, defining thestate of the VM's virtual processor. Extended Page Tables (EPTs) areused to map memory addresses from Guest Physical Addresses (GPAs) knownto the guest, to the Physical Addresses (PAs) used to address thephysical memory.

Virtual machine 3530 _(T) is an example of a typical implementation of avirtual machine, which is managed by VMM 3522 using VMCS 3524 and EPTs3526, both of which are under the sole control of VMM 3522. Virtualmachine 3530 _(T) is referred to herein as a “trusting” virtual machine,because while VM 3530 _(T) is managed by and under the control of VMM3522, no mechanism exists for VM 3530 _(T) to verify that VMM 3522 hasnot been compromised. Consequently, virtual machine 3530 _(T) must trustthat the actions of VMM 3522 will not compromise the consumer's workloador data or reveal consumer secrets. In addition, the code for VMM 3522is considered to be a part of the consumer VM's Trusted Code Base (TCB).

In contrast to VMCS 3524 used by VMM 3522, each of virtual machines VM13530 ₁, VM2 3530 ₃, and VM3 3530 ₄ and agent virtual machines 3530 ₂ and3530 ₅ includes protected memory regions and a respective data structurereferred to herein as a “control structure.” Each of VM1 3530 ₁, VM23530 ₃, and VM3 3530 ₄ includes protected memory regions (key domains)containing respective control structures VMCS/EPTs 3540 ₁, VMCS/EPTs3540 ₃, and VMCS/EPTs 3540 ₄. Similarly, agent virtual machines 3530 ₂and 3530 ₅ include respective control structures VMCS/EPTs 3540 ₂ andVMCS/EPTs 3540 ₅ within their protected memory regions. While thesecontrol structures VMCS/EPTs 3540 ₁₋₅ are shown as a combination of aVMCS with EPTs, the control structures may include a separate datastructure for the VMCS from the EPTs. The control structures may alsoinclude other extended control structures such as a VirtualizationException Information Page, an Extended Page Table Pointer (EPTP) Listfor VMFunctions, Model-Specific Register (MSR) bitmaps, Input/Output(I/O) bitmaps, MSR load and store pages, or any future control structureextensions to the VMCS.

The processor appends the key domain identifier/address selector for thecurrently executing guest VM to the uppermost portion of these addressesspecified in the VMCS.

While VMM 3522 manages the instantiation of each of the non-trusting andagent virtual machines 3530 ₁₋₅, the consumer, or their trustedintermediary, provides the control structures 3540 ₁₋₅ to be used tocontrol execution of the consumer's virtual machine and, in particular,to define the state of each VM's virtual processor.

Virtual machines VM1 3530 ₁, VM2 3530 ₃, and VM3 3530 ₄ and agentvirtual machines 3530 ₂ and 3530 ₅ are executed within cryptographicallyprotected regions of memory 3512 referred to as key domains, such as KD13550 ₁ and KD2 3550 ₂. A key domain key is used to encrypt and decryptthe data in each key domain.

Each non-trusting guest virtual machine, such as non-trusting VM1 3530₁, along with the associated control structures VMCS/EPTs 3540 ₁, ishosted inside a key domain. This hosting scheme cryptographicallyprotects the non-trusting guest virtual machine and associated controlstructures from tampering by a compromised virtual machine monitor.Furthermore, placing control structures for each virtual machine intothe same key domain as the associated virtual machine enables eachvirtual machine to verify actions taken by the virtual machine monitorwith regard to the control structures.

The key domain provides a protected environment in which a consumervirtual machine can operate with the consumer's confidence that theconsumer's workload and data are protected. Similarly, the virtualmachine monitor managing the consumer virtual machines can ensure thatno consumer virtual machine has corrupted the cloud service provider'sserver platform hardware, or software or firmware running on theplatform hardware.

A consumer virtual machine such as non-trusting VM1 3530 ₁ can verifyactions requested by the untrusted cloud service provider's virtualmachine monitor 3522 with respect to control structure 3540 ₁. The cloudservice provider's virtual machine monitor 3522 remains in control ofthe platform, manages execution of the consumers' virtual machines (suchas non-trusting VM1 3530 ₁, non-trusting VM2 3530 ₃, and non-trustingVM3 3530 ₄,) and can verify that the consumer's virtual machine has notcorrupted a virtual machine control structure.

Key domains KD1 3550 ₁ and KD2 3550 ₂ each also include an agent guestvirtual machine, respectively agent 3530 ₂, having its own controlstructure 3540 ₂, and agent 3530 ₅, having its own control structure3540 ₅. Because virtual machine monitor 3522 cannot read data encryptedwithin a key domain, virtual machine monitor 3522 uses agent guestvirtual machines 3530 ₂ and 3530 ₅ to act on behalf of VMM 3522 withinthe respective key domain KD1 3550 ₁ or KD2 3550 ₂. In particular,virtual machine monitor 3522 uses agent guest virtual machines tomanipulate a control structure of a protected virtual machine. Forexample, virtual machine monitor 3522 may use agent 3530 ₅ to manipulatethe control structure of non-trusting VM3 3530 ₄ within key domain KD23550 ₂. Virtual machine monitor 3522 may use the consumer's agent tomanipulate the control structure of a virtual machine in the process ofswitching execution to the virtual machine, resuming execution of thevirtual machine after pausing execution, and so on.

A key domain such as KD1 or KD2 cryptographically separates virtualmachines for each consumer from one another, as well as from the cloudservice provider's virtual machine monitor. Similarly, actions taken bythe non-trusting consumer virtual machine can be verified by the cloudservice provider's virtual machine monitor. This mutual verificationenables the cloud service providers to provide a public cloudenvironment that consumers can trust as protective of consumer virtualmachine workloads and data, while enabling the cloud service provider toconfirm that the activities of the consumer virtual machine have notcorrupted the public cloud environment.

In one embodiment, the host VMM/agent relationship is established duringsystem initialization. Trusted agent code, data, extended page tablesand an initial VMCS are loaded into memory and measured. In oneembodiment, the measurements of the trusted agent code, extended pagetables, and VMCS are performed during a launch sequence for Intel®'sTrusted Execution Technology (TXT). TXT may also measure other statesuch as the state of a System Transfer Monitor to protect against SystemManagement Mode (SMM) based accesses; BIOS and VMM measurements may alsobe taken. Finally, the agent establishes a secret value with the CPUthat is stored in a hidden register and is used to identify a validagent-authorized VMCS. Once a measured agent is loaded into theprotected memory region (key domain), a VMM can be loaded outside thekey domain and unprotected (trusting) guest VMs can be run normally.

Alternatively, when the protected memory region is an aliased memoryencryption region, a secure enclave, such as provided by Intel®'sSoftware Guard Extensions (SGX), may load an already encrypted memoryimage into memory. When the secure enclave knows the memory encryptionkey domain key, the secure enclave can load and attest a VM image atruntime. The encrypted memory image may contain the VMCS, EPTs and code.

Similarly, the consumer, knowing the memory encryption key and using theCreate Key Domain (CreateKD) instruction described herein, can encryptthe consumer's own image which can be loaded by the cloud serviceprovider's software into plaintext memory that aliases to the keydomain. The consumer image contains the VMCS, EPT and code imageencrypted with the key domain key such that it is not accessible by thecloud services provider. The cloud services provider's host VMM may thenload (via a VMPTRLD instruction) the consumer's VMCS in the key domain.The memory encryption engine will decrypt the VMCS structure from theconsumer's encrypted image on memory reads (VMReads). The host VMM canverify the contents of the consumer's VMCS, and then the host VMM cancall VMLaunch, which will enable the key domain key and pull theremainder of the consumer's image through the memory encryption engine,decrypting the consumer's image into cache as it executes. Either aVMLaunch or VMResume instruction will enable the specified key domainkey (thus properly decrypting the memory contents).

In an embodiment in which the guest VM's protected memory region isprotected using range registers, running the agent within the protectedmemory region has a different behavior. Only VMLaunch (and/or VMResume)of a guest VM can drop the range register protections to allow the guestVM to execute when a valid control structure (VMCS) resides within thekey domain. When the guest VM exits (via VMExit) the range registerprotections are re-enabled before returning control to the host VMM.Write operations (VMWrites) from the host VMM directly to the protectedVMCS are either limited or denied. As an optimization, some embodimentsmay allow limited write operations (VMWrites) to those regions of theVMCS that will not compromise the security of a guest VM, for example,restricting VMWrites from the host VMM exclusively to the host statearea of the VMCS.

Editing a VMCS for a protected guest VM requires cooperation from theagent. A clear operation (VMClear) will return the cached VMCS into theguest VM's protected memory region (key domain). Then the host VMM caninvoke the guest VM via VMLaunch (using the agent's VMCS). The agent canperform edits to the VMCS within the protected memory region (keydomain) and verify the host state as well (e.g., using VMCS shadowVMRead/VMWrite or editing the in-memory VMCS structure).

When the agent has completed the edits to the VMCS, the agent can return(via a VMCall or VMExit) back to the host VMM. At this point, the hostVMM can load the VMCS pointer (VMPTRLD) again and use VMReads to verifythat the host state of the VMCS was not maliciously tampered with by theagent (i.e., verify that the host VMM's VMCS is correct/in an expectedstate). Meanwhile, read operations (VMReads) of the guest state area ofthe VMCS may be denied because the VMCS is within the key domain andguest VM state is to be hidden from the host VMM. If the VMCS is valid,the host VMM may then VMLaunch the agent-edited VMCS and resume theguest VM.

Hash Key Domain (HashKD) is an instruction used by the host VMM to “readthrough” the mechanisms protecting the protected memory region whilemaintaining confidentiality. In an embodiment protected by rangeregisters, the processor range register protecting the guest VM's memoryregion will not block memory reads when originating from the HashKDinstruction. In an embodiment protected as a key domain, the memory isencrypted, but the processor will allow the HashKD instruction to accessthe memory and decrypt it (for the purpose of generating a SHA2/3 hashof the memory's contents). The Hash Key Domain (HashKD) instruction canbe used to assure the VMM that guest-formed structures, such as newEPTs, match the host VMM's expectations, and will not allow guest accessto the host or other guests. The hash doesn't reveal the memorycontents/secrets (unknown values), but if the hash value matches astructure the host already knows/expects, then the host VMM can beassured that memory was configured correctly by the guest agent, andlaunch the guest VM with the corresponding VMCS that references thevalidated EPT or any other control structure.

Using these techniques, the agent can create additional VMCSs andadditional EPT structures for multiple guest VMs within a protectedmemory region (key domain), load consumer images into those guest VMs,and so on. The host VMM may then launch guest VMs using these VMCSsafter validating their EPT's and/or other control structures using aHash Key Domain (HashKD) instruction. Each of the guest VMCSs maycontain a secret value shared between the agent and the CPU (and storedin a hidden register configured with the secret value when the keydomain is created (Create Key Domain (CreateKD) instruction isexecuted). This secret value is validated when the VMPTRLD instructionis executed; only if the secret shared between the agent and the CPU isfound will the VMCS be considered to be valid. In this way, a protectedguest VM cannot collude with the host VMM to create its own VMCS. Norcan a malicious VMM send data to a protected VM (e.g. via an I/O orcommunications channel) that happens to be formatted as a VMCS and,thereby, undermine the guest's security. Additional fields can be addedto the VMCS to allow the agent to control whether the host VMM canresume a guest VM. Resume operations (VMResumes) can be restricted bythe guest VM, requiring the agent to first be run and reset the VMCSfield before a VMCS can be re-launched by the host VMM.

Exit (VMExit) flows can be modified to first save (e.g., execute anXSAVE instruction) all processor register state, or guest interrupthandlers/“shims” can be inserted by the agent to assure that allprocessor register state is saved to protected memory and cleaned beforereturning control to the host VMM. For an unrestricted guest VM, theshim can intercept all interrupts and save and clean the guest registerstate before returning control to the host VMM (via VMCall). In oneembodiment, Intel®'s Virtual Exceptions (#VE) can also be used tointercept all EPT violations and redirect those back to the guest shimwhere processor state may be saved to an encrypted memory area andcleared before transferring control by to the VMM via a VMCall. Thistechnique prevents exposure of the guest VM's register state to thehost.

Finally, multiple register ranges and/or multiple key domains can alsobe established, allowing multiple non-trusting guest VMs to be isolatedfrom one another. When a control structure (VMCS) is loaded via aVMPTRLD instruction, the location of the VMCS determines which range orkey domain is accessible after VMLaunch. Each key domain is thenresponsible for its own security having its own VMCSs, EPTs andcode/data. Host VMM protection is assured by verifying a VMCS beforelaunching a guest VM controlled by the VMCS and verifying the associatedEPTs and other control structures (using HashKD) are correctlyconfigured to restrict guest VM access to the host VMM and other guestVMs.

The memory protected by range registers may only be an alias back tohost memory (e.g. the alias uses a high order unused address bit). Thisalias bit (or bits, referred to above as “k-bit(s)”) is used by thememory encryption engine to determine whether the memory is to beencrypted with a secret key on writes, or decrypted on reads. In thisway, the host VMM and its guest VMs share the same physical memory, butthe protected guest VM contents are protected from host VMM accessbecause the guest VM contents are encrypted in memory by the memoryencryption engine using the guest VM's secret key domain key. Accessingmemory through the host alias (e.g., with the high order physicaladdress bit unset), disables the memory encryption engine leaving theencrypted contents encrypted. Conversely, if the encrypted memory isaccessed by the guest VM with the high order address bit set, then thememory contents are first decrypted by the memory encryption engineusing the secret key, leaving plaintext in the cache with the high orderbits of the address corresponding to the key domain identifier/addressselector. Meanwhile, the protected guest VMs can access memory througheither the encrypted or plaintext aliases, allowing guest VMs tocommunicate with the host VMM and other guest VMs by accessing hostmemory regions (as controlled by the guest VM's EPTs verified by thehost VMM via HashKD). Alternatively, a known shared key domain (or thehost VMM's key domain) can be used for communication between the hostVMM and the guest VMs.

The techniques disclosed herein enable a consumer's workload and secretsto be protected without exposing the consumer's key domain key used toencrypt the consumer's image, VMCS, EPTs, code and data. The key domainidentifier/address selector is not exposed to the host VMM, nor does thekey domain identifier appear in physical addresses of control structures(such as Extended Page Table or Virtual Machine Control Structure). Thekey domain identifier/address selector is used when a VMM enters aprotected VM, where the VMM establishes the VM's key identifier whenloading the VMCS via the a VM Pointer Load (VMPTRLD) instruction. If theVMCS decrypts properly (is not corrupt or invalid and/or the secretvalue inside the VMCS is correct), the hardware is using the correct keydomain key (identified by the key domain identifier/address selector),and the key domain identifier/address selector is associated with thecurrent key domain.

Using these techniques, an unlimited number of consumer key domains maybe encrypted in memory. Keys are reprogrammed in the memory encryptionengine for an available key domain identifier/address selector slot. Forexample, when a VM can be suspended so that it is not executing on anycores, the cache contents for that VM can be flushed. Then a Create KeyDomain (CreateKD) instruction can be called by the VMM to establish adifferent key for the suspended VM's key domain identifier/addressselector. In this way, suspended VMs can be scheduled

To summarize the techniques used herein, the initial launch orresumption of a guest virtual machine (or agent) within a protectedmemory region (key domain) causes the hardware (e.g., a page misshandler) to set unused bits of a respective physical address for eachmemory location allocated to the guest virtual machine (or agent) to akey domain identifier/address selector. The key domainidentifier/address selector identifies a protected memory region (keydomain) in which data for the guest virtual machine (or agent) isencrypted by a key domain key. The unused bits of the physical addressesare set to the key domain identifier/address selector except in caseswhere the guest virtual machine's (or agent's) Extended Page Tables(EPTs) designate that encryption is to be turned off.

When a guest virtual machine (or agent) is to be initially launched orresumed, the key domain identifier/address selector is specified by theunused bits of an address provided in a VM Pointer Load (VMPTRLD)instruction that loads a control structure (VMCS) for the guest virtualmachine (or agent) to be launched or resumed. In response to the VMPTRLDfunction call, CPU hardware reads the VMCS inside the key domain bysetting the key domain identifier/address selector in the physicaladdress. If the VMCS is invalid or corrupted, the host VMM will rejectthe requested VMPTRLD function call to load the VMCS. If the VMCS isvalid, the VMCS will be written to cache for use by the agent or guestVM that is to be launched, the guest address space identifier will beflushed, and the guest state cleared so that the new VMCS can configurethe address space and guest state for the newly-launched VM or agent.

Exiting the guest VM (or agent) causes the hardware (e.g., the page misshandler) to stop using the key domain identifier/address selector in theaddress or to switch back to the host VMM's key domain.

The agent is loaded and measured (e.g., by Intel®'s Trusted ExecutionTechnologies (TXT), Software Guard Extensions (SGX) or ManageabilityEngine), or is simply included as an already encrypted in-memory imageby the consumer for managing the consumer's VMs. The agent isXTS-encrypted for the key domain using the correct physical memoryaddresses as tweaks, runs as a guest VM, and manages the controlstructures (VMCS and EPTs) for the guest VMs that the agent protects.The consumer can trust the agent to provide measurements and attest tothe validity of the host VMM, securely exchange private keys, load theconsumer's encrypted domain image into a key domain, and maintainprivacy of the consumer's workload and data.

In one embodiment, a guest virtual machine, such as an agent, can use ashim (such as an interrupt descriptor table hook) to interceptinterrupts. A shim may be a driver in the guest operating system. Theguest VM can create its own shim (a driver or code that interceptsinterrupts/exceptions), or the agent can create a shim on the guest VM'sbehalf. The agent can also have its own shim (a driver or code to handleinterrupts/exceptions, etc.). The shim runs as an unrestricted guest,handles interrupts and virtualization exceptions, causes VM exits usingVMCall instructions, uses a virtualization exception handler tointercept Extended Page Table violations, uses a VMFunc function toswitch into other Extended Page Tables, and assures that the generalpurpose register and XMM state that may hold confidential data are savedand cleaned before a transfer back to the host VMM is made via a VMCallinstruction. A shim may selectively, depending on the context, exposesome guest state to the host. For example, if a virtual device driveraccessed device space with a register value that describes an I/O memorylocation to be used for DMA by a virtual device, this register data canbe exposed to the host VMM (instead of being saved and cleared).

These features enable the “blinded” host VMM/hypervisor to remain incontrol of the platform. The host VMM can, for example, refuse to launcha guest virtual machine that does not have a valid or verifiable controlstructure (VMCS/EPT). Furthermore, the host VMM can set a “VM preempt”timer to pre-empt execution of a guest virtual machine and returncontrol to the host VMM.

FIG. 36 shows a data flow for a virtual machine monitor (host VMM) toaccess a virtual machine control structure for a guest virtual machinerunning within a protected key domain. Because host VMM 3622 has noaccess to the protected memory (key domain KD1 35501) where the agent36302 resides, host VMM 3622 requests agent VM 36302 to interact withthe control structure 36401 for non-trusting VM1 36301 on its behalf.

In action “VMRead” 36.1, host VMM 3622 is allowed to read the controlstructure VMCS/EPTs 36401, even though VMM 3622 does not possess thedecrypted key domain key, without requesting gent VM 36302 to read thecontrol structure VMCS/EPTs 36401 on its behalf. Processor microcode mayallow read operations to be performed into the cached VMCS so that thehost VMM can verify the VMCS before entry. A read operation does notexpose confidential information about the guest VM (because the GPRregister state is saved elsewhere, inaccessible to the host VMM). Theread operation (VMRead) allows the host VMM to verify that the agentcorrectly edited a VMCS as the host VMM requested. An alternative to theread operation (VMRead) is to use a Hash Key Domain (HashKD) instructionto verify (by matching hash values) that the in-memory VMCS matches whatthe host VMM expects. Whether or not the host VMM uses an agent to readthe control structure, the host VMM is allowed to verify but not modifythe VMCS/EPTs.

In action “VMWrite” 36.2, VMM 3622 is not allowed to write data directlyto the VMCS/EPTs 36401. Instead, in action “Request VMWrite” 36.3, VMM3622 sends a VMWrite request to Agent 36302 to write to the controlstructure VMCS/EPTs 36401. In action “Request EPT Edit” 36.4, VMM 3622requests Agent 36302 to edit the EPTs within VMCS/EPTs 36401. In“VMWrite” action 36.5, agent 36302 performs the requested edit of theEPTs within VMCS/EPTs 36401. In some embodiments, limited writeoperations (VMWrites) may be allowed by the host VMM, for example, bythe CPU limiting host VMM write operations to those fields of the VMCSthat have no effect on the guest VM's behavior. For example, the CPU mayexclusively allow the host VMM to write to the host state area of theVMCS. Any write operations that affect the guest's security require theagent to perform.

FIG. 37 shows a process for an agent acting on behalf of a virtualmachine monitor to edit a virtual machine control structure for a guestvirtual machine running within a protected key domain. Two types ofshading are shown for each block; a line fill pattern is used to showactions under control of the host VMM, whereas a dot fill pattern showsthat control has passed to the guest VM executing within the protectedkey domain.

At “VMLaunch VM” block 3710, the process begins with the host VMMlaunching a guest virtual machine. In one embodiment, to launch theguest virtual machine, the VMM first issues a command to execute a VMPointer Load (VMPTRLD) instruction, which provides a pointer to aconsumer-provided control structure (such as a VMCS) for the guest VM,thereby setting the current VMCS and key domain identifier/addressselector. As a result of executing the VM Pointer Load instruction, theCPU caches the VMCS. If the VMCS is invalid or corrupted, the host VMMwill reject the requested VMPTRLD function call to load the VMCS. If thecontrol structure/VMCS is within the protected memory region (keydomain), the key domain identifier/address selector is appended byhardware to each physical address belonging to the guest VM beinglaunched. Once the current VMCS is established, the VMM issues a commandto execute a VMLaunch or VMResume instruction (which are alternativelyreferred to herein as a VMEntry or VMEnter instruction).

Upon entering the guest VM, the key domain can be said to be “turnedon,” similar to the Switch Key Domain (SwitchKD) instruction describedearlier. As shown by the transition from a line fill pattern to a dottedfill pattern in “VMLaunch” block 3710, control transitions from the hostVMM to the guest VM within the key domain when the guest VM is launched.The VMCS is written to cache and the guest address space identifier isset, or else the guest TLB is cleared. The guest VM then executes untilthe guest VM has completed its workload.

At “(Time Passes) VMExit” block 3720, the guest VM finishes executing,and control returns to the host VMM. As shown by the transition from adotted fill pattern to a line fill pattern in “(Time Passes) VMExit”block 3720, control transitions from the guest VM within the key domainback to the host VMM when the guest VM finishes executing. A VMExit isusually an asynchronous event caused by something the guest VM does(such as accessing an invalid, protected or paged-out memory region) orby an external event (such as an interrupt that is not handled by theguest VM or expiration of a preemption timer). Alternatively, a guest VMmay issue a command to execute a VMCall instruction that causes a typeof VMExit. When the guest VM exits, the key domain identifier/addressselector is reset to the host VMM's key domain or the guest VM'sprotected memory range registers are re-enabled and control is returnedto the host VMM.

Upon exiting a guest VM, and before returning control to the “root”/hostVMM, microcode reprograms hardware (such as a page miss handler) to setthe host VMM's or shared key domain on all physical addresses (exceptwhere an indicator (such as the k-bit described above) is set to turnencryption off). When returning control back to the host VMM, theguest's key domain key should no longer be used, nor should the guestVM's key domain identifier/address selector be used. Either the key forthe host VMM is used, or encryption is turned off (k-bit off).Effectively, the CPU switches out of the guest VM's key domain (similarto an implicit Switch Key Domain) to the cloud service provider (hostVMM's) key domain. Because the host VMM “root” is running underneath theguest VM that is exiting, control returns to the host VMM, switching thekey domain back to the host VMM's key domain or to shared unencryptedmemory (e.g., the shared bit indicator (k-bit) is off).

The host VMM executes a VMClear command at “VMClear” block 3730 to savethe state of the guest VM from cache into memory. As part of the VMClearcommand, the host VMM provides a pointer to the key domain in which theguest VM was executing and checks for a valid control structure (VMCS)within the key domain or that the VMCS was already cached for the sameaddress.

The pointer provided with the VMClear instruction should be the same asthe pointer originally used to load into cache the VMCS with the VMPTRLDinstruction, where the key domain ID was already appended to thepointer, which is a physical memory address, including the key domainID. It is important that VMClear does not send a VMCS from one memorylocation to another, or from one key domain to another, as these actionswould be an attack. Thus, the VMClear instruction uses the same pointeras given with the VMPTRLD instruction and cached by the processor or theprocessor will first need to verify that a valid VMCS is in the memorylocation being VMCleared for the specified key domain identifier/addressselector.

If the VMCS is valid, and the pointer matches the memory address and keydomain identifier/address selector of the cached VMCS, the host VMMflushes the VMCS to memory using the key domain identifier/addressselector in the physical address so that the state of the guest virtualmachine is saved within memory of the key domain. The VMCS may not becached because not all processors will explicitly cache the VMCS; someprocessors will access the VMCS from memory. If the VMCS is not cached,the host VMM may perform consistency checks by reading the memory usingthe key domain identifier/address selector in the physical address tocheck for an invalid/corrupt VMCS (e.g., the secret value inside theVMCS does not match one of the values established in the processor'shidden register when the key domain was created (on execution of theCreateKD instruction)).

The processor first checks the VMCS by reading it before writing theVMCS to memory is to ensure that the VMCS is valid and not corrupted.For example, the VMCS will be corrupted if the host VMM specified thewrong key domain identifier/address selector, and therefore the VMCSdecrypted incorrectly, or if the host VMM specified the wrong memorylocation for the VMCS. If invalid or corrupt VMCS data is found, thehost VMM will receive an error and the VMCS will not be used by theprocessor.

Control proceeds from “VMClear” block 3730 to “VMPTRLD Agent VMCS” block3740. The VMPTRLD instruction provides a physical address of a VMcontrol structure (VMCS) for an agent to be loaded into memory. If theaddress of the agent VM control structure is inside a key domain, unusedbits of the physical address include the key domain identifier/addressselector.

As described above, the agent's code and control structure (VMCS) areprovided to the host VMM by the consumer as part of the consumer'sencrypted domain image, and the correct memory location of the VMCS isprovided to the host VMM. The host VMM then proceeds to “VMEnter Agent”block 3750.

After confirming that the control structure (VMCS) to which the VMpointer load (VMPTRLD) instruction refers is valid, the host VMM willissue a VMEnter command (which may be either a VMLaunch or a VMResumecommand) to execute the agent within the protected memory region (keydomain). The processor will use the key domain ID in the addresses(thus, allowing the agent to access the properly decrypted memory). Inan embodiment in which the protected memory region is provided by rangeregisters, the VMEnter instruction will disable the range registerprotections to run an agent within the protected memory region only ifthe agent's VMCS is inside the protected memory region and contains asecret value known only to the CPU and agent. As shown by the transitionfrom a line fill pattern to a dotted fill pattern in “VMEnter Agent”block 3750, control transitions from the host VMM to the agent withinthe key domain when the agent is launched. Once the agent is in controlwithin the key domain, the host VMM is “blind” to activity that occurswithin the consumer's guest VM.

A host VMM may launch an agent within a key domain to request the agentto act on behalf of the host VMM to control execution of another guestVM executing within the protected memory region (key domain). To controlexecution of the other guest VM, the host VMM requests the agent to edita control structure of the other guest VM. This request from the hostVMM can be made in many forms, in accordance with agreed-upon softwareconventions between the cloud services provider and the consumer. Forexample, the request may be placed into an in-memory structure orcommand queue, or the request can include an entire VMCS to be copiedfrom the host VMM's memory into the guest's protected key domain memory.Alternatively, the host VMM's request may be encoded in the processorregisters (e.g. GPRs).

At “Agent Reads Request from Host” block 3760, the agent reads therequest from the host VMM to edit the other guest VM's controlstructure. As noted above, the request may have been made in severalforms, in accordance with agreed-upon software conventions between thecloud services provider and the consumer.

The agent proceeds to “Agent Edits VMCS Inside KD” block 3770, where theagent edits the control structure (VMCS) of the other guest VM withinthe key domain. This permission to read and write (using VMRead andVMWrite instructions) to the guest VM's control structure may beaccomplished using VMCS shadowing. Without VMCS shadowing, a guest VMsuch as the agent normally cannot execute VMRead and VMWriteinstructions, as the VMRead and VMWrite are intended for use by a hostVMM running in VMXRoot mode. Because VMCS is an in-memory structure, aguest VM executing within the same key domain could directly edit theVMCS on behalf of the host VMM; however, for security reasons, at leastone embodiment limits the ability to edit the VMCS to an agent.

After completing the edit of the other guest VM's control structure, theagent exits by executing a VMCall instruction, returning control back tothe host VMM, as shown by the transition from a dotted fill pattern to aline fill pattern in “VMExit” block 3780. VMExits back to the host VMMre-enable the protected memory region provided by the encrypted keydomain, blocking host VMM accesses not only to the agent's code/data,VMCS, and Extended Page Tables (EPT), but also to the code/data, VMCS,and EPTs of the guest VMs that are protected by the agent.

Upon receiving control back from the agent, at “VMPTRLD Edited VMCSInside KD” block 3790, the host VMM first executes a VMPTRLD instructionwith the address/pointer (including the key domain identifier/addressselector) of the VMCS that was edited. The VMPTRLD instruction loads theedited control structure (VMCS) inside the key domain. Only then can thehost VMM execute the VMRead instruction to verify that the agent madethe edits to the other guest VM control structure as requested by thehost VMM. Even though data in the key domain is encrypted and the hostVMM does not have the decrypted key domain key, the host VMM is allowedto read portions of the in-memory VMCS control structure using a VMReadinstruction.

After confirming that the guest VM control structure has been edited asrequested, control then returns to “VMLaunch VM” block 3710, where thehost VMM launches the guest VM to execute in accordance with the editedcontrol structure as provided by the host VMM.

In some embodiments, write operations (VMWrites) may be restricted fromthe host VMM to the protected VMCS, requiring the host to always ask theagent to perform any edits to the VMCS on the host's behalf. In suchembodiments, if the host VMM requests to perform a write operation to aVMCS inside a key domain, the write operation will be blocked. In otherembodiments, limited write operations (VMWrites) by the host VMM may beallowed to specific VMCS fields (such as fields in the host state areathat do not affect security of the guest VM).

The host VMM is allowed to perform a store operation (VMPTRST) to storethe current (cached) VMCS pointer from the VMPTRLD instruction to aspecified address in memory, which must be outside the protected orencrypted memory of the guest VM. The key domain is not specified aspart of the physical address for a VMPTRST operation.

FIG. 38 shows an interrupt handler/shim for a guest virtual machine toselectively protect the guest VM's processor register state (such asGeneral Purpose Registers (GPRs)) from modification by a compromisedvirtual machine monitor. If a VMExit is triggered, the interrupthandler/shim is invoked prior to exiting the guest VM, giving the guestVM an opportunity to conditionally save and protect its processorregister state before exiting to the host VMM. In the example shown,each of non-trusting guest virtual machines VM1 3830 ₁ and VM2 3830 ₂,and agent 3830 ₃ within key domain 3550 ₁ has its own respectiveinterrupt handler/shim 3835 ₁, 3835 ₂, and 3835 ₃. Rather than a VMExitinstruction causing the respective host VMM to be instantiated, VMExitinstructions are redirected to the respective interrupt handler/shim,which uses software to hide the guest VM's processor state from the hostVMM 3822. One example of an interrupt handler/shim is a VirtualizationExceptions (#VE) driver described in U.S. Patent Application Publication2015/0121366.

Each of interrupt handlers/shims 3835 ₁, 3835 ₂, and 3835 ₃ may performa General Purpose Register save or restore operation. In one embodiment,each guest VM runs as an unrestricted guest, intercepts all interrupts,uses a virtualization exception handler to intercept EPT violations,uses VMFunc to switch Extended Page Tables, and assures that GeneralPurpose Register and other register states are conditionally savedand/or cleaned before transferring execution to a host VMM 3822 via aVMCall instruction.

FIG. 39 shows an implementation of the interrupt handler/shim of FIG.38. Non-trusting VM1 3930 causes a VMExit condition, resulting in avirtualization exception to be redirected back to the guest's interrupthandler/shim 3935. This redirection is considered to be a “guest-inducedexit” rather than a VMM-induced exit. In one embodiment, guest-inducedexits cause a virtualization exception, and interrupt handler/shim 3935handles the virtualization exception. Interrupt handler/shim 3935 mayinclude the virtualization exception handler (#VE) code (not shown),bypassing the host VMM. After the virtualization exception handler #VEhandles the virtualization exception, control returns to interrupthandler/shim 3935, which conditionally saves and cleans the processorregister values (e.g. GPRs) before making a VMCall to return control tothe host VMM. The host VMM can then issue a command to execute aVMResume instruction, which will resume non-trusting VM1 3930, includinginterrupt handler/shim 3935. Interrupt handler/shim 3935 causes theregister values to be restored and returns control to non-trusting VM13930, for example, by using a IRET instruction.

In one embodiment, virtualization exception handler #VE may interceptEPT violations, as well as CPUID and other guest-induced exitconditions. Virtualization exception handler #VE may decide whichGPR/XMM register state is saved and/or cleaned before transferringcontrol back to the host VMM by issuing a command to execute a VMCALLinstruction. In this way, non-trusting VM1 3930 can decide the aspectsof the CPU state that are to be exposed to the host VMM.

FIG. 40 shows a data flow during operation of the interrupt handler/shimdriver of FIGS. 38 and 39. With regard to saving the encrypted state,some data within key domain 4050 will be register state information.Host VMM-specific exits (not requiring emulation, such as, for example,a preemption timer event) can automatically save CPU state. For example,the CPU can save all register state information to the VE InformationArea 4033 (such as a 4 KB page), then clear the register state, set theVMCS to restore the register state on re-entry, and then exit the guestVM 4030. The host VMM 4022 will handle VMExit and VMResume instructions.Upon receiving a command to execute a VMResume instruction to resume agiven VM, the CPU will check the VMCS, restore the guest VM's processorstate from the VE Information Area 4033, and resume the guest VM.

FIG. 41 is a diagram showing messages between components of a cloudservice environment to encrypt a consumer-provided code image andestablish a key domain in accordance with one embodiment of theinvention. The data flows described for FIG. 41 are similar to the dataflows described above for FIG. 13, although the data flows are in thecontext of a cloud services provider's host VMM and a consumer-providedimage to be run as a guest virtual machine providing an agent. Note thatthe same data flows apply whether the consumer-provided image is for anagent to be run as a guest virtual machine or for any other consumerworkload to be run as a guest virtual machine.

The consumer 4101 requests protected services from the cloud servicesprovider, and in response, the cloud service provider's software, suchas, for example, the host VMM 4122, provides memory locations for theguest agent image, Virtual Machine Control Structure (VMCS) and ExtendedPage Tables (EPTs). Given these memory locations, the consumer 4101edits the VMCS and EPTs to be used to instantiate the guest agent imageon the cloud services provider's servers.

In one embodiment, the guest agent image, including the controlstructure VMCS and EPTs, is then encrypted by the consumer 4101 using amemory position-dependent “tweaked” cipher (e.g., XTS) and theconsumer's key domain key. The VMCS and EPTs are embedded within theguest agent image in the embodiment shown, although the VMCS and EPTsmay be provided separately as long as they are encrypted using theconsumer's key domain key.

The consumer 4101 may also calculate integrity check values (ICVs, e.g.,keyed-hash message authentication codes (HMAC) values) for the encryptedguest agent image using the key domain key. The ICVs may be calculatedas position-dependent values and are used to verify the position as wellas the contents of the associated memory locations for the encryptedguest agent image.

The consumer 4101 requests the cloud services provider host VMM 4122 toidentify a server in the cloud services provider's network that provideskey domain management functionality. The cloud services provider hostVMM 4122 obtains a server certificate for a key domain-capable server(in this example, from a server having CPU 4111) and provides the servercertificate to the consumer 4101. The consumer 4101 verifies that theserver certificate is signed by an authority certifying that theidentified server provides key domain management functionality inaccordance with at least one embodiment.

The consumer 4101 encrypts the consumer's key domain key (as well as anyother consumer secret data such as the secret value stored within theVMCS) with the cloud services provider's key domain-capable server'spublic key corresponding to the key domain-capable server's certificate.The consumer 4101 sends the encrypted key domain key, encrypted guestagent image (including EPTs and VMCS), and (optionally) integrity checkvalues (ICVs) to the cloud services provider host VMM 4122, which issuesa Create Key Domain (CreateKD) command to the CPU 4111 of the keydomain-capable server. In one embodiment, the cloud services providerhost VMM 4122 identifies a key domain address selector to use for thenew key domain, providing the key address domain selector to the CPU4111 of the key domain-capable server. The CPU 4111 of the keydomain-capable server creates and initializes a key domain. Initializingthe key domain may include flushing caches of any previous key domain(identified by the previous key domain address selector) as well asflushing translation look-aside buffers that cached address mappings forthe previous key domain. Initializing the key domain may also includeprogramming the memory encryption engine with the decrypted key domainkey as well as configuring hidden registers in the CPU corresponding tothe secret value uniquely identifying the consumer's guest agentVMCS(s).

As an alternative to performing initialization functions as part of theCreate Key Domain instruction, the CPU 4111 of the key domain-capableserver may execute an Initialize Key Domain (InitKD) instruction toflush the caches and translation look-aside buffers.

The host VMM 4122 executing on CPU 4111 may also provide the consumer'sencrypted guest agent image (including EPTs and VMCS) and integritycheck values directly to memory 4112. The consumer's guest agent imageis already encrypted, so that the consumer's guest agent image can bewritten directly to memory as if it were plaintext, bypassing the memoryencryption engine TMEi 4115. Alternatively, the consumer's encryptedguest agent image may pass through the memory encryption engine TMEi4115 with the encryption bit (k-bit) of the physical address turned off,so that the memory encryption engine TMEi 4115 treats the consumer'sencrypted guest agent image as unencrypted plaintext. When theconsumer's guest agent image is read later from memory 4112 using thecorrect key domain key, then the memory encryption engine TMEi 4115 willdecrypt the content (as the encrypted VMCS/control structure is beingread and the consumer's guest agent image is being executed by the CPU4111).

FIG. 42 shows an alternative embodiment for creating a key domain. Inthis example, a secure enclave (such as an enclave created usingIntel®'s Software Guard Extensions (SGX)) creates the guest imagelocally on the cloud services provider's server. Consumer 4210 firstobtains a certificate from enclave 4290 running on the cloud servicesprovider's server. Consumer 4210 then verifies the enclave certificate,and sends the guest image to the enclave 4290 via a secure mechanismsuch as a Secure Sockets Layer connection. Enclave 4290 obtains thememory locations for the guest image, VCMS, and EPTs from the cloudservices provider's host VMM (not shown), and programs a local keydomain key. Enclave 4290 then issues a command to execute a create keydomain instruction to CPU 4211. When creating the new key domain, localCPU 4211 flushes caches of the previous key domain address selector andprograms the memory encryption engine TMEi 4215 with the key domain keyfor the address selector.

Enclave 4290 then creates the VMCS and EPTs for the guest image andre-encrypts the image (containing the VMCS and EPTs) using the keydomain key that enclave 4290 previously determined. In the embodimentshown, enclave 4290 also calculates integrity check values for the guestimage using the key domain key. Enclave 4290 then provides the encryptedguest image, including the VMCS and EPTs, to the cloud serviceprovider's host VMM (not shown, but executing on CPU 4211).Alternatively, any other Trusted Execution Environment (TEE), such as amanageability engine (ME) or Converged Security Engine (CSE), couldperform the same functions herein ascribed to the Enclave TEE. Likewise,a trusted third party server or service can produce the encrypted memoryimages on behalf of the consumer for instantiation on the cloud serviceprovider's infrastructure.

As above for FIG. 41, host VMM (not shown) executing on CPU 4211 mayalso provide the consumer's encrypted guest image (including EPTs andVMCS) and integrity check values directly to memory 4212. The consumer'sguest image is already encrypted, so that the consumer's guest image canbe written directly to memory 4212 as if it were plaintext, bypassingthe memory encryption engine TMEi 4215. Alternatively, the consumer'sencrypted guest image may pass through the memory encryption engine TMEi4215 with the encryption bit (k-bit) of the physical address turned off,so that the memory encryption engine TMEi 4215 treats the consumer'sencrypted guest image as unencrypted plaintext. When the consumer'sguest image is read later from memory 4212 using the correct key domainkey, then the memory encryption engine TMEi 4215 will decrypt thecontent (as the encrypted VMCS/control structure is being read and theconsumer's guest agent image is being executed by the CPU 4211).

FIG. 43 shows one embodiment of a process for the host VMM to verify theconsumer-provided agent VMCS. The cloud services provider's host VMM4322 issues a command to CPU 4311 to execute a VM Pointer Load (VMPTRLD)instruction using the consumer-provided agent's control structure (VMCS)address and key domain identifier/address selector located in theconsumer's encrypted memory image. Memory encryption engine TMEi 4315uses selected bits (such as the uppermost unused bits) of the physicaladdress specified via the VMPTRLD instruction for the VMCS as the keydomain identifier/address selector. Memory encryption engine TMEi 4315reads the encrypted data line from memory 4312 and decrypts the dataline (using a memory-position dependent cipher such as XTS, describedabove) using the key domain key determined from the key domainidentifier/address selector. If the VMCS decrypts correctly, CPU 4311then caches the VMCS, and the cloud services provider's host VMM 4322performs a VMRead of the VMCS to ensure that the VMCS is correctlyconfigured for host VMM 4322. If the VMCS is correctly configured, hostVMM 4322 issues a command to execute a VMLaunch instruction to CPU 4311to launch the agent using the consumer-provided agent VMCS. CPU 4311then runs the agent as a guest VM.

The verification of the agent control structures (VMCS/EPTs) describedwith regard to FIG. 43 above may be performed alternatively using a HashKey Domain (HashKD) instruction. In an implementation using HashKD, theCPU would execute a HashKD instruction of the memory locations where theVMCS/EPTs were initially installed to determine an expected hash value,create another hash value from the data produced in response to a readinstruction, and verify that the two hash values match, therebyverifying the control structures (VMCS/EPTs).

Once the agent control structures (VMCS and EPTs) are verified by thehost VMM, the host VMM trusts the agent. The agent can then be launchedby the host VMM and used to modify the consumer's image by adding codeor data to modify the functionality of the consumer's guest VM.

While the description of FIG. 43 pertains to verifying an agent VMCS,the same data flows apply to any consumer-provided guest VMCS to be usedto launch a guest virtual machine.

FIG. 44 provides an example of data flows of the host VMM requesting anagent to modify control structures (VMCS/EPTs) for another guest VM. Theprocess described uses EPTs as an example of the control structure beingmodified, but the same process applies to both EPTs and VMCSmodifications, as well as to modifications of any other controlstructures or memory contents of the guest VM.

When a guest VM 4402 exits and returns control to the cloud serviceprovider's host VMM 4422, an EPT entry may indicate that a page is notpresent. As an example, the EPT entry may be set to indicate that amemory page is not present because the page was previously paged out bythe host VMM. If the guest VM attempts to access the address for thatnon-present page, the associated EPT entry will reveal that the page isnot present, causing a VMExit to occur. The goal of the host VMM, asshown in FIG. 44, is to replace the original page back into memory andthen reset the exiting EPT entry to indicate the page is now present ata specified address so that the host VMM can resume the execution of theguest VM with the accessed page back in memory.

Upon receiving control, the CPU (not shown) will restore the host statefor host VMM 4422 from the control structure (e.g., VMCS, not shown)with which it is associated. Host VMM 4422 may later decide to resumeguest VM 4402, and send a message to an agent 4403 working on behalf ofthe host VMM 4422 within the key domain of guest VM 4402 to be resumed.The host VMM 4422 tracks which guest VMs have exited (in this example,guest VM 4402) because the host VMM 4422 launched the guest VMs,including guest VM 4402, initially. The host VMM 4422 also tracks thekey domain to which each guest VM belongs because the host VMM 4422specified the key domain identifier/address selector as part of theaddress used in the VM Pointer Load (VMPTRLD) instruction used to loadthe VMCS for the guest VM. The host VMM 4422 also tracks the agent for agiven key domain and the associated guest VMs in that given key domain.

To resume guest VM 4402, host VMM 4422 prepares a message to the agent4403 to edit the guest VM 4402's EPT and performs a clear operation(issuing a command to execute a VMClear instruction) to clear the guestVM 4402's VMCS from a per processor VMCS cache (not shown). As part ofthe clear operation, the guest VM 4402's VMCS is also returned to cache4413 on its way back to memory 4412, along with the key domainidentifier/address selector. The key domain identifier/address selectorwill be used as part of a selected set of bits (such as the uppermostunused bits) of the physical address to which the VMCS is ultimatelywritten to indicate to the memory encryption engine which key domain keyto use. Memory encryption engine TMEi 4415 writes the encrypted VMCS,along with integrity check values for embodiments that have integrity,to memory 4412.

After issuing the command to execute a VMClear instruction, host VMM4422 performs two operations. In the first operation performed by hostVM 4422, host VMM 4422 places an unencrypted (k-bit off, also designatedas !k) request into a memory location that is shared with the agent 4403(which may be in cache 4413 or memory 4412), specifying the requestededits for VM 4402's EPT. In the example shown, memory encryption engineTMEi 4415 writes the plaintext request into a memory location in memory4412. Later, agent 4403 will retrieve the requested edits for VM 4402'sEPT from memory 4412. In addition to the EPT edit request, the host VMM4422 may provide additional information to the agent, including theencrypted page contents that are to be paged back into memory.

In the second operation performed by host VM 4422, host VMM 4422 issuesa command to execute a VMPTRLD instruction, providing a pointer to theagent 4403's VMCS and the key domain identifier/address selector, whichdetermines the key to be used to decrypt agent 4403's VMCS. Agent 4403'sVMCS is read from memory 4412 by memory encryption engine TMEi 4415,which decrypts the agent 4403's VMCS using the key domainidentifier/address selector specified in the VMPTRLD instruction. HostVMM 4422 obtains the decrypted VMCS produced by memory encryption engineTMEi 4415. In response to correctly loading the agent's VMCS, host VMM4422 issues a command to execute the VMLaunch instruction, whichlaunches the agent 4403 using the properly decrypted agent VMCS as thecontrol structure. The CPU running the agent 4403 code restores theguest state of the associated virtual processor from the decrypted agentVMCS.

In the example shown, agent 4403 causes the request data to be read frommemory 4412. In one embodiment, agent 4403 checks a command queuelocation in memory, and finds another request from the host VMM 4422there, and then agent 4403 responds to the command by causing therequest data to be read from memory. The request could also becommunicated to the host VMM 4422 as a processor register state (e.g.,via a GPR register state), which the host VMM 4422 could use to triggeragent 4403 to read the request from memory. Other embodiments may usedifferent mechanisms to communicate to agent 4403 that there is anoutstanding host VMM 4422 request.

The unencrypted request data is read from cache by agent 4403, and agent4403 processes host VMM 4422's request to edit guest VM 4402's EPTs.Agent 4403 writes the EPT edits for VM 4402 to memory 4412 via memoryencryption engine TMEi 4415, which causes the encrypted EPTs andassociated integrity check values to be written to memory 4412.Alternatively, agent 4403, which has access to the memory encryption keyand memory locations of the EPT entries, may simply use the memoryencryption key to encrypt the edited EPT structures and communicate thisciphertext (the encrypted edited EPT structures) back to the host VMM4422 via a shared memory channel.

The agent 4403 may also decrypt any encrypted page contents provided bythe host VMM 4422 that are to be paged back into memory. For example,the agent 4403 may decrypt the pages using a different secret key thatthe agent 4403 uses for paging, using the guest physical address (GPA)address as a tweak. The agent 4403 may also verify the page contents oruse ICVs to verify that the page contents were not modified since theywere last paged-out and encrypted with the same secret key and tweak.The agent 4403 may then either write the decrypted page(s) to memory,assuming the agent has access to these memory locations, or the agentmay re-encrypt the pages using the memory encryption key and physicaladdress tweak, returning the resulting ciphertext back to the host VMM4422 via a shared memory channel. Having completed the request to editthe EPTs made by host VMM 4422, agent 4403 has completed its task andexits, returning control to host VMM 4422.

The CPU executing the VMExit restores the host VMM 4422 state from thehost state area of the agent 4403's VMCS. The host VMM 4422 optionallymay issue a command to execute a VMClear instruction to clear agent4403's VMCS. As part of the clear operation, agent 4403's VCMS iswritten to Cache 4413 with the key domain identifier/address selector.The encrypted agent VMCS and associated integrity check values arewritten to memory 4412 by the memory encryption engine 4415.

Host VMM 4422 may then verify that the agent 4403 correctly edited theEPTs for VM 4402 by issuing a command to execute a Hash Key Domain(HashKD) instruction on the memory locations where VM 4402's EPTs wereto be modified or on the locations where the host VMM installed the EPTciphertext provided by the agent. Memory encryption engine TMEi 4415uses the key domain identifier/address selector as the address selectorto read the encrypted data for the associated key domain. Memoryencryption engine TMEi 4415 reads the encrypted data line, decrypts thedata, and sends the decrypted data to cache 4413 for the address and keydomain identifier/address selector.

The processor executing the HashKD instruction reads the decrypted dataobtained by memory encryption engine TMEi 4415, and the host VMM 4422verifies that a hash value of the contents of the memory locations readmatches the hash value for the expected EPT contents. At this point, thehost VMM 4422 may also write to the correct memory locations anyciphertext for the pages re-encrypted by the agent 4403 and returned viashared memory (for cases where the agent does not have access to thememory to install the pages itself). If the hash values match, host VMM4422 issues a command to execute a VMPTRLD instruction for the VM 4402'sVMCS. At this point, the host VMM may then re-verify the contents of theVMCS using VMReads. Host VMM 4422 then issues a command to launch theguest VM 4402 from the VM 4402's VMCS. The processor executing the codefor VM 4402 restores the state of VM 4402's virtual processor from VM4402's VMCS and executes VM 4402 using the modified EPTs, which nowindicate that the pages are present and identify the memory addresses inwhich the pages are located.

The memory transactions described with reference to FIG. 44 may residein cache 4413, thereby eliminating the need for the memory encryptionengine (TMEi 4415) to read and write data from cache 4413 to memory4412, and vice versa. Nevertheless, the above memory transactions aredescribed as though data for each transaction is evicted from cache 4413into memory 4412.

Some embodiments may also enable Page Modification Logging (PML) so thatthe host VMM can track memory locations accessed by a guest agent. Thenumber of Hash Key Domain (HashKD) instructions can be limited to onlythose memory locations that were actually modified while the agent wasexecuting. Here the PML address and log page would remain in the hostVMM's key domain (or shared memory/k-bit off), so that the VMM can trackthe actions of the guest VM.

Similarly, some embodiments may use a sub-page policy table (SPPT) [asdescribed in U.S. Pat. No. 9,335,943 B2] to allow the host VMM toadditionally restrict the memory locations an agent can access. In suchembodiments, the host VMM would control the SPPT and an agent could begiven access to memory via its EPTs, with the agent's VMCS indicatingthat an additional SPPT is enabled. The sub-page protection tablepointer in the VMCS would use the host VMM's key domain (or sharedmemory/k-bit off). The agent's EPT entries include the SPP bit set foreach entry that the host VMM can override write access using the hostVMM's SPPT.

FIG. 45 is a flowchart showing execution of the VM Pointer Load(VMPTRLD), VMEnter (VMLaunch or VMResume), and VMExit instructions. Atblock 4505, in response to a VMPTRLD instruction providing a VMCSaddress, the key domain identifier/address selector from the VMCSaddress is used to access the VMCS. At decision point 4510, a decisionis made whether VMCS decrypted correctly by verifying the VMCS'scontents (which can include a version number and the secret value sharedbetween the agent and the processor and stored within the agent VMCS, asdescribed above with reference to FIG. 37, “VMEnter Agent” block 3750).If the VMCS did not decrypt correctly, control proceeds to block 4515,where an error is returned to the host VMM issuing the command toexecute the VMPTRLD instruction. If the VMCS decrypted correctly,control proceeds to block 4520, which optionally caches the VMCS. Inblock 4525, an optional VMRead instruction is executed by the host VMMto verify contents of the VMCS.

From block 4520, control proceeds to block 4530, where a VMEnterinstruction is executed. A virtual machine is instantiated (typicallyeither launched or resumed) using the key domain identifier/addressselector from the address in the VMPTRLD instruction to access the VMCSfor entering the virtual machine (if the VMCS was not already cached atblock E20). If the VMCS was already cached at block 4520, block 4530 canuse the cached VMCS to instantiate the virtual machine.

At decision point 4535, a decision is made whether the VMCS is corruptor invalid because the processor will perform other consistency checkson the VMCS when attempting to restore the guest's processor state. Ifthe VMCS is corrupt or invalid, control proceeds to block 4540, where anerror is returned to the host VMM. If the VMCS is not corrupt orinvalid, control proceeds to block 4545. At block 4545, the CPU pipelineis flushed. An address space identifier tag is set for transactionlook-aside buffers (TLBs) given the key domain identifier/addressselector or the TLBs are flushed. CPU registers are set to the VMCSguest state. Additionally, if there is a Virtualization Exception (VE)Information Page indicated by its physical address in the VMCS, and theVMCS indicates that additional guest state is currently stored there,the remainder of the processor registers will be restored from the VEInfo Page. Restoring the processor registers includes adding the currentkey domain identifier/address selector to the VE Info Page address. TheExtended Page Table Pointer (EPTE) is a physical address for the base ofthe EPT table. Because the EPT table is inside the key domain of theguest VM, this address should likewise include the key domainidentifier/address selector so that the EPT structures decrypt properly.

Control proceeds from block 4545 to block 4550, where a branch toexecute at the guest state instruction pointer (IP) is made. Executioncontinues until an exit condition to exit the currently-executingvirtual machine, and control proceeds to block 4555. As with any VMExit,guest processor state is stored to the current VMCS. If there is a VEInfo Page present and the exit was not due to a VMCall, then theremainder of the guest's processor register state may be saved to the VEInfo Page and then these registers cleared. From block 4555, controlproceeds to block 4560. At block 4560, the CPU pipeline is flushed. Anaddress space identifier tag is set for VMXRoot or the TLBs are flushed.The current key domain is set to the host VMM key domainidentifier/address selector in embodiments where the host VMM has itsown key domain identifier/address selector. In other embodiments, wherethe host VMM is in unencrypted memory, the k-bit is set to “off” and thekey domain identifier/address selector address bits are cleared. CPUregisters are set to the cached VMCS host state. Control proceeds fromblock 4560 to block 4565, where a branch to execute at the host stateinstruction pointer (IP) is made.

In FIG. 45, EPTs remain under the host VMM's control (as normal). Toprevent memory remapping attacks, some embodiments may add a new table(called a Reverse Mapping Table, not shown), which is accessed by theprocessor (Page Miss Handler (PMH)) on a page walk. After the addressmappings are determined by the page walk, the resulting physical addressis checked against an entry in the Reverse Mapping Table (RMT) indexedby the resulting physical address. The entry includes the physicaladdress and its associated guest physical address (and the permissionbits and/or k-bit) expected by the consumer (and/or consumer's agent).If the PMH determines that the guest physical address (GPA) orpermissions do not match those determined by the completed page walk,then the CPU will exit (executing a VMExit instruction indicating theerror). This RMT entry is accessed by the processor/PMH using the keydomain ID belonging to the executing guest VM. Thus, each RMT tableentry must be XTS encrypted using the consumer's key, so that only theconsumer or the consumer's agent can produce these RMT entries as theyapply to the consumer's key domain.

Referring now to FIG. 46, a process for updating a consumer's guest VMimage is shown. The process begins after the consumer's initial codeimage 4631 has been established to run within key domain 4650 as a guestVM 4630 ₁, which can only access the memory that is mapped and grantedpermission in the Extended Page Tables (EPTs) provided by the consumeras part of the encrypted guest control structure. To enable theconsumer's guest VM 4630 ₁ to provide additional functionality,additional code can be added to the guest VM 4630 ₁ code image 4631.Because guest VM 4630 ₁ has access to only the portion of memory withinkey domain 4650, however, the cloud service provider's host VMM 4622 andguest agent 4630 ₂ are involved to update the guest VM's code image4631.

As noted above, the consumer's encrypted guest code image may includecode for launching a second guest, the guest agent. Once the guest agent4630 ₂ is running as a guest agent virtual machine within the consumer'sencrypted key domain 4650, the guest agent 4630 ₂ can perform severaltasks on behalf of the host VMM 4622. Guest agent 4630 ₂ performs taskson behalf of the host VMM 4622 as requested, as long as the tasks do notcompromise the consumer's guest VM 4630 ₁. Host VMM 4622 can verify thattasks performed by the agent 4630 ₂ have been performed as requested.Consequently, host VMM 4622 does not need to provide the code image foragent 4630 ₂ or to trust agent 4630 ₂.

As examples of tasks that can be performed by agent 4630 ₂ on behalf ofhost VMM 4622, agent 4630 ₂ can create other guest virtual machinesinside key domain 4650, request more memory from the host VMM 4622, andmove memory pages to the consumer guest VM 4630 ₁ workload from theconsumer or a consumer-authorized third party. For example, agent 4630 ₂can securely communicate the consumer-encrypted remainder of the guestVM code image 4604 to the consumer's guest VM 4630 ₁. The encryptedremainder of the VM code image 4604 may be communicated first via asecure connection (e.g., a Transport Layer Security/Secure Sockets Layer(TLS/SSL) session)) established between the consumer and the guest agent4630 ₂. Host VMM 4622 copies the encrypted packets and bufferscontaining the remainder of the VM code image 4604 to shared memory4612U for retrieval by the guest agent 4630 ₂. Guest agent 4630 ₂terminates the TLS/SSL session by decrypting the data contained in theencrypted packets and buffers.

Running within key domain 4650, the guest agent 4630 ₂ can access thememory encryption key domain key used by the consumer (as the consumercreated the initial guest VM image with that key domain key in FIG. 41).Using the key domain key, the agent 4630 ₂ may separately XTS encryptadditional data/code/structures (with the appropriate memory addresstweaks). The guest agent 4630 ₂ can then provide the resultingciphertext to the host VMM 4622 (for example, via shared memory channel4612U, as shown by the “write memory” arrow from agent 4630 ₂ throughshared memory 4612U). The host VMM 4622 can then install that ciphertext(which the host VMM 4622 cannot decrypt as the host VMM 4622 doesn'thave the key domain key) into the appropriate memory locations (at theaddresses for which they are encrypted), as only the host VMM 4622 hasaccess to all of memory, including unencrypted shared memory 4612U.

For example, to change the memory locations to which the guest agent4630 ₂ has access, the host VMM 4622 can request the guest agent 4630 ₂to generate the appropriate ciphertext (using the consumer's memoryencryption key domain key) for the new EPT data and address tweaks (andcalculate the Integrity Check Values (ICVs) if integrity is desired).The host VMM 4622 would then copy the ciphertext to memory at thecorrect locations on behalf of the guest agent 4630 ₂ as only the hostVMM 4622 has the ability to address all memory. Once the updated agentEPTs are correctly installed, then the guest agent 4630 ₂ would havedirect access to these new memory locations.

A similar process is followed to restrict the memory locations that theguest agent 4630 ₂ may access, as the host VMM 4622 may request theguest agent 4630 ₂ to create ciphertext for selected EPT structures todesignate the selected EPT structures as not present (no permission orno mapping). In all cases, once the ciphertext is installed into thecorrect memory locations, the host VMM 4622 can verify the contents ofthe ciphertext using the Hash Key Domain (HashKD) command describedabove.

The cloud service provider's host VMM 4622 is in control of the system,memory and other resources, but the guest agent 4630 ₂ is in control ofproducing data of which the guest agent 4630 ₂ approves, as only theguest agent 4630 ₂ has the memory encryption key domain key and can passthis approved encrypted data to the host VMM 4622.

For systems with System Management Mode (SMM) or similar privilegedmodes enabled, SMM should not have access to a consumer's key or keydomain identifier/address selector. Similarly, when a System ManagementInterrupt (SMI) occurs during the execution of a consumer's guest VM,the guest processor register state should be saved to memory locationsinaccessible to SMM and cleared.

FIG. 47 describes another process for a consumer to add pages to theconsumer's guest VM workload. In the example shown, packets for the restof the consumer's guest VM image are sent by the consumer to the hostVMM 4722 directly (via a secure communication session between theconsumer and the guest agent as described above with respect to FIG.46). In response, the host VMM 4722 writes the data for the rest of theconsumer's guest VM image to memory 4712 via memory encryption engineTMEi 4715.

Host VMM 4722 issues a command to launch a guest agent on CPU 4711, andCPU 4711 begins executing the guest agent code image provided by theconsumer as part of the encrypted guest VM code image to provide guestagent 4703. Host VMM 4722 sends the rest of the consumer's guest VMimage through a shared (encryption bit (k-bit) off) portion of memory4712. The running agent 4703 reads data for the rest of the consumer'sguest VM image from the host VMM 4722's shared portion of memory 4712(not encrypted, with k-bit off) by requesting the memory encryptionengine TMEi 4715 to read the data from an address with the uppermostunused bits set to a key domain identifier/address selector for theshared (k-bit off) key domain. As the agent 4703 is the endpoint for asecure communication session with the consumer, the agent 4703 decryptsthe network packets (e.g., using the OpenSSL software library) into theshared memory region. The running agent 4703 copies the resultingdecrypted data to encrypted memory (encrypted with the consumer's keydomain key, with k-bit on) at an address with the uppermost unused bitsset to a key domain identifier/address selector for the consumer's keydomain. During the first write to a new memory address, the MOVNTinstruction may be used to perform a write-combining operation, whichwrites to the new memory address in memory 4712 without first readingthe contents of the new memory address that is to be written. Memoryencryption engine TMEi 4715 then writes the encrypted data for the restof the consumer's guest VM image, along with integrity check values(ICVs), to memory 4712.

Agent 4703 process the data (for example, decrypting the data insoftware, performing integrity checks, and so on). The consumer forms asecure communication session (for example, using a TLS/Secure SocketsLayer session from the consumer using the consumer's encryption key (keydomain key) to the agent image's TLS stack), and packets are sent via acontroller through the shared memory (not encrypted, with k-bit off).

The above embodiments describe an environment in which a consumer cantrust that its secrets and data are as secure in the public cloud as ina private cloud environment. A consumer (or the consumer's trustedintermediary) can provide an encrypted guest virtual machine (VM) imagethat can be installed in a protected region of memory (referred to as akey domain) in which memory pages are encrypted with a consumer-providedkey domain key. The consumer's encrypted guest virtual machine image canbe decrypted by the cloud service provider server's processor using thekey domain key that is provided to the host VMM by the consumer only asan encrypted key domain key. The consumer's guest VM can be verified bya cloud service provider's software/host virtual machine monitor (VMM),without the host VMM being exposed to the encryption key domain key orthe contents of the encrypted guest virtual machine image and thesecrets contained therein. The consumer's encrypted guest virtualmachine image can be executed using processor state informationdecrypted by the processor from within consumer-provided controlstructure(s) that are also provided to the host VMM encrypted with theconsumer's key domain key.

The control structure information encrypted with the consumer's keydomain key may contain memory mapping structures (Extended Page Tables(EPTs)).

A processor executing the consumer's encrypted guest virtual machineimage may encounter a situation where an exit from the guest VM to thehost VMM is needed. When the guest's VM is exited, the host processorautomatically switches the current key domain back to either the hostVMM's key domain or to a shared key domain shared between the host VMMand each guest virtual machine managed by the host VM. In an exit of theguest VM, the consumer-provided guest control structure specifies aprotected memory location where the host processor may automaticallystore and clear processor registers on exits to the host VMM.

In one embodiment, the guest VM code image contains interrupt handlercode to intercept interrupts and convert guest VM exits to exceptions,where the guest VM may save processor register information to protectedmemory and clear or conditionally expose processor registers needed bythe host VMM. When the guest VM has completed preparation for saving theguest VM's processor state, the guest VM can invoke the host VMM.

In one embodiment, the consumer-provided encrypted guest VM image andguest control structure can be dynamically updated or modified bysending encrypted image updates or encrypted control structure updates(deltas) that are installed and verified by the host VMM into the host'smemory. The encrypted image update may serve as a replacement for theguest VM's encrypted code image, or the encrypted image update may be a“delta” image that is used to modify the guest VM's encrypted codeimage.

Dynamic updates to the encrypted guest control structure may beinitiated by either the host VMM or the guest VM. For example, the hostVMM may determine that the guest code image should be moved to adifferent memory location. Moving the guest code image to a differentmemory location affects Extended Page Tables (EPTs) of the guest controlstructure. The guest VM can verify the change to the guest controlstructure and provide an updated encrypted guest control structure tothe host VMM. The host VMM can copy the guest-provided updated encryptedguest control structure into the appropriate memory locations.

As an example of a dynamic update to the encrypted guest controlstructure initiated by a guest VM, the guest VM may request more memoryfrom the host VMM. In response to this request, the host VMM maydetermine that the Extended Page Tables (EPTs) of the guest controlstructure must be modified. The guest VM can verify the allocation ofadditional memory and the resulting change to the guest controlstructure and provide an updated encrypted guest control structure tothe host VMM. The host VMM can copy the updated encrypted guest controlstructure into the appropriate memory locations.

A shared communication channel can be established between a protectedguest VM and the host VMM using, for example, a bit of a physicaladdress for a memory location to indicate whether the memory location isto be shared. In one embodiment, the bit may be turned off to indicatethat the memory location is to be shared, and the bit may be turned onto indicate that the memory location is to be protected (encrypted).

Requests for changes to the consumer-provided guest control structure orguest VM image can be sent over the shared communication channel betweenthe host VMM and a protected guest VM. A protected guest VM can verifythat such requests do not compromise the security of the guest VM, andthe guest VM can produce ciphertext for the requested changes using thekey domain key. The guest VM can then provide the ciphertextimplementing the requested changes to the host VMM. The host VMM caninstall the guest VM-provided ciphertext into memory and verify that therequested changes were completed correctly by the guest VM (e.g. using aHash Key Domain (HashKD) instruction). Once the ciphertext is verified,the host VMM can then execute the modified guest VM image.

In one embodiment, the consumer-provided encrypted guest VM image maycontain code to implement a second guest VM (agent) that has access tothe consumer-provided guest VM's memory (key domain). This agent isprovided by the consumer to enable the host VMM to request the agent toperform tasks on behalf of the host VMM. The host VMM can communicaterequests to the agent over shared communications channel. The host VMMcan request the agent to modify control structures or contents of memoryof a second guest VM (or third guest VM, and so on) on the host VMM'sbehalf. The agent can verify that host VMM requests to change memory ofa guest VM do not compromise the consumer's security policy. The hostVMM can verify changes were correctly made to memory by the agent (forexample, via a HashKD instruction) and then execute the modified guestVM.

In addition, the agent can perform memory paging operations upon requestby the host VMM. For example, the agent can “page out” a page (usuallycontaining 4 KB of data) of protected memory, encrypting contents of theprotected memory using a second key for offline storage. In this pagingout scenario, the agent provides an encrypted page to the host VMM viathe shared memory channel. The agent can also perform “paging in”operations on the host VMM's request, decrypting memory content providedby the host VMM via the shared memory channel with a second key,verifying the content, and installing the decrypted content intoprotected memory.

In each of the above embodiments, the cryptographic memory protectionprovided to key domains may optionally includes integrity verification,where integrity check values (ICVs) can be used to verify the contentsof a memory location.

The following paragraphs pertain to further embodiments.

In Example 1, an apparatus to securely execute a consumer workload in apublic cloud environment without exposing data or secrets of theconsumer includes a processor; and a memory coupled to the processor;where the processor is to execute an untrusted host virtual machinemonitor to manage execution by the processor of at least one guestvirtual machine; the untrusted host virtual machine monitor is toreceive an encrypted key domain key, an encrypted guest code imageencrypted by a key domain key, and an encrypted guest control structureencrypted by the key domain key, the key domain key inaccessible to theuntrusted host virtual machine monitor; the untrusted host virtualmachine monitor is to issue a create command to the processor to createa first key domain, the first key domain comprising a region of thememory to be encrypted by the key domain key, the untrusted host virtualmachine monitor to further verify the encrypted guest control structure;in response to receiving the create command, the processor is to createthe first key domain and decrypt the encrypted key domain key to producethe key domain key; the untrusted host virtual machine monitor is toissue a launch command to the processor to launch a first guest virtualmachine within the first key domain; and in response to receiving thelaunch command, the processor is to switch to the first key domain,decrypt the encrypted guest control structure to produce a guest controlstructure containing guest processor state information, decrypt theencrypted guest code image to produce a guest code image, and executethe guest code image within the first key domain using the guestprocessor state information.

Example 2 includes the apparatus of Example 1, where the untrusted hostvirtual machine monitor is to verify the encrypted guest controlstructure by issuing a command to the processor to execute at least oneof a Hash Key Domain instruction and a VM Read instruction.

Example 3 includes the apparatus of Example 1, where in response to anevent triggering an exit condition of the first guest virtual machine,the processor is to switch from the first key domain to a second keydomain.

Example 4 includes the apparatus of Example 3, where the second keydomain is unencrypted; and the second key domain is a shared region ofthe memory shared by the untrusted host virtual machine monitor and eachguest virtual machine managed by the untrusted host virtual machinemonitor.

Example 5 includes the apparatus of Example 3, where the second keydomain is encrypted by a second key domain key for the untrusted hostvirtual machine monitor; the second key domain key is accessible to theuntrusted host virtual machine monitor and to each guest virtual machinemanaged by the untrusted host virtual machine monitor; and the secondkey domain is a shared region of the memory shared by the untrusted hostvirtual machine monitor and each guest virtual machine managed by theuntrusted host virtual machine monitor.

Example 6 includes the apparatus of Example 3, where the guest controlstructure specifies a protected location of the memory where theprocessor may store the guest processor state information.

Example 7 includes the apparatus of Example 6, where, in response to anevent triggering an exit condition of the first guest virtual machine,the processor is to save the guest processor state information for thefirst guest virtual machine in the protected location of the memory; theuntrusted host virtual machine monitor is to issue a resume command tothe processor to resume the first guest virtual machine; and in responseto receiving the resume command, the processor is to switch to the firstkey domain, retrieve the guest processor state information for the firstguest virtual machine from the protected location of the memory, andexecute the guest code image within the first key domain using the guestprocessor state information.

Example 8 includes the apparatus of Example 3, where the guest codeimage includes interrupt handler code to intercept an interrupt; theprocessor is to convert an exit condition of the first guest virtualmachine to an exception; the guest code image is to save processorregister information to the protected location of the memory in responseto at least one of the interrupt and the exception; the guest code imageis to clear a first processor register if the first processor registeris not needed by the untrusted host virtual machine monitor; the guestcode image is to conditionally expose a second processor register if thesecond processor register is needed by the untrusted host virtualmachine monitor; the guest code image is to invoke the untrusted hostvirtual machine monitor; and the first guest virtual machine is to exitwhen the untrusted host virtual machine monitor is invoked.

Example 9 includes the apparatus of Example 3, where the untrusted hostvirtual machine monitor is to receive an encrypted updated guest controlstructure, install the encrypted updated guest control structure in thememory, and verify the encrypted updated guest control structure; theprocessor is to decrypt the encrypted updated guest control structure toproduce an updated guest control structure; in response to verifying theencrypted updated guest control structure, the untrusted host virtualmachine monitor is to issue an enter command to the processor to enterthe first guest virtual machine using the updated guest controlstructure; and in response to receiving the enter command, the processoris to enter the first guest virtual machine using the updated guestcontrol structure.

Example 10 includes the apparatus of Example 9, where the untrusted hostvirtual machine monitor is further to receive an encrypted updated guestcode image and to install the encrypted updated guest code image in thememory; the processor is to decrypt the encrypted updated guest codeimage update to produce an updated guest code image; and the processoris to enter the first guest virtual machine by executing the updatedguest code image using the updated guest control structure.

Example 11 includes the apparatus of Example 3, where the untrusted hostvirtual machine monitor is to determine whether a change to the guestcontrol structure is needed; the first guest virtual machine is toverify that the change to the guest control structure does notcompromise security of the first guest virtual machine; the first guestvirtual machine is to produce an encrypted updated guest controlstructure incorporating the change using the key domain key; and thefirst guest virtual machine is to send the encrypted updated guestcontrol structure to the untrusted host virtual machine monitor via ashared region of the memory shared by the untrusted host virtual machinemonitor and the first guest virtual machine.

Example 12 includes the apparatus of Example 11, where the untrustedhost virtual machine monitor is to install the encrypted updated guestcontrol structure in the memory; the untrusted host virtual machinemonitor is to verify the encrypted updated guest control structure; theprocessor is to decrypt the encrypted updated guest control structure toproduce an updated guest control structure; in response to verifying theencrypted updated guest control structure, the untrusted host virtualmachine monitor is to issue an enter command to the processor to enterthe first guest virtual machine using the updated guest controlstructure; and in response to receiving the enter command, the processoris to enter the first guest virtual machine using the updated guestcontrol structure.

Example 13 includes the apparatus of Example 12, where the untrustedhost virtual machine monitor determines whether the change is needed tothe guest control structure in response to a request received from thefirst guest virtual machine.

Example 14 includes the apparatus of Example 13, where the requestfurther includes a second change to the guest code image; the firstguest virtual machine is to verify that the second change to the guestcode image does not compromise security of the first guest virtualmachine; the first guest virtual machine is to produce an encryptedupdated guest code image incorporating the second change using the keydomain key; and the first guest virtual machine is to send the encryptedupdated guest control image to the untrusted host virtual machinemonitor via the shared region of the memory.

Example 15 includes the apparatus of Example 14, where the untrustedhost virtual machine monitor is to receive the encrypted updated guestcode image; the processor is to decrypt the encrypted updated guest codeimage to produce an updated guest code image; and the processor is toexecute the guest code image by executing the updated guest code image.

Example 16 includes the apparatus of Example 15, where the encryptedguest code image includes an agent code image; the encrypted guestcontrol structure includes an agent control structure; the untrustedhost virtual machine monitor is to verify the agent control structure;the untrusted host virtual machine monitor is to issue a second launchcommand to the processor to launch a second guest virtual machine withinthe first key domain, the second guest virtual machine to provide anagent to act on behalf of the untrusted host virtual machine monitorwithin the first key domain; and in response to receiving the secondlaunch command, the processor is to switch to the first key domain,decrypt the encrypted guest code image to produce the agent code image,decrypt the encrypted guest control structure to produce the agentcontrol structure containing agent processor state information, andexecute the agent code image within the first key domain using the agentprocessor state information.

Example 17 where the apparatus of Example 16, where the untrusted hostvirtual machine monitor is to communicate a request to modify the guestcontrol structure of the first guest virtual machine to the agent via ashared region of memory shared by the agent and the untrusted hostvirtual machine monitor; in response to reading the request from theshared region of memory, the agent is to modify the guest controlstructure of the first guest virtual machine within the first key domainto produce a modified guest control structure of the first guest virtualmachine; the untrusted host virtual machine monitor is to verify themodified guest control structure of the first guest virtual machine;upon verifying the modified guest control structure, the untrusted hostvirtual machine monitor is to issue an enter command to the processor toenter the first guest virtual machine within the first key domain; andin response to receiving the enter command, the processor is to executethe guest code image within the first key domain using second guestprocessor state information from the modified guest control structure.

Example 18 includes the apparatus of Example 16, where the untrustedhost virtual machine monitor is to communicate a request to the agent toretrieve a page from encrypted storage, where each page of the encryptedstorage is encrypted by a storage key; the agent is to decrypt the pageusing the storage key to produce a decrypted page; the agent is toverify the decrypted page; and if the decrypted page is verified, theagent is to install the decrypted page into the memory.

Example 19 includes the apparatus of Example 18, where if the agent hasaccess to a location in the memory into which the decrypted page is tobe installed, the agent is to copy the decrypted page into the locationof the memory; and if the agent does not have access to a location inthe memory into which the decrypted page is to be installed: the agentis further to re-encrypt the page using the key domain key and aphysical address of the location as a tweak to produce a re-encryptedpage; and the untrusted host virtual machine monitor is to install there-encrypted page into the memory.

Example 20 includes the apparatus of Example 16, where the untrustedhost virtual machine monitor is to communicate a request to the agent tomove a page from encrypted memory to storage, where each page of theencrypted memory is encrypted by the key domain key; the agent is todecrypt the page using the key domain key to produce a decrypted page;the agent is to verify the decrypted page; and if the decrypted page isverified, the agent is to re-encrypt the decrypted page with a storagekey for the storage to produce a storage-encrypted page, move thestorage-encrypted page to the storage, and provide the storage-encryptedpage to the untrusted host virtual machine monitor.

Example 21 includes the apparatus of Example 1, where the untrustedvirtual machine monitor is to issue a load command to the processor toload the encrypted guest control structure into the memory, the loadcommand comprising a pointer to a physical address in the memory fromwhich to load the encrypted guest control structure and a key domainidentifier for the first key domain; and, in response to receiving theload command, the processor is to determine a key domain keycorresponding to the key domain identifier, where the processor is touse the key domain key to decrypt the encrypted guest control structure.

Example 22 includes the apparatus of Example 1, where the processor isfurther to confirm integrity of the encrypted guest control structure.

Example 23 includes a processor to securely execute a consumer workloadin a public cloud environment without exposing data or secrets of theconsumer, the processor to execute an untrusted host virtual machinemonitor to manage execution by the processor of at least one guestvirtual machine; create a first key domain in response to a createcommand issued by the untrusted host virtual machine monitor, the firstkey domain comprising a region of a memory to be encrypted by a keydomain key, the key domain key inaccessible to the untrusted hostvirtual machine monitor; decrypt an encrypted key domain key receivedfrom the untrusted host virtual machine monitor to produce the keydomain key; launch a first guest virtual machine within the first keydomain in response to a launch command issued by the untrusted hostvirtual machine monitor, where to launch the first guest virtual machineincludes to: switch to the first key domain, decrypt an encrypted guestcontrol structure received from the untrusted host virtual machinemonitor to produce a guest control structure containing processor stateinformation, decrypt an encrypted guest code image received from theuntrusted host virtual machine monitor to produce a guest code image,and execute the guest code image within the first key domain using theprocessor state information.

Example 24 includes the processor of Example 23, where the processor isfurther to switch from the first key domain to a second key domain inresponse to an event triggering an exit condition of the first guestvirtual machine.

Example 25 includes the processor of Example 24, where the second keydomain is unencrypted; and the second key domain is a shared region ofthe memory shared by the untrusted host virtual machine monitor and eachguest virtual machine managed by the untrusted host virtual machinemonitor.

Example 26 includes the processor of Example 24, where the second keydomain is encrypted by a second key domain key for the untrusted hostvirtual machine monitor; the second key domain key is accessible to theuntrusted host virtual machine monitor and to each guest virtual machinemanaged by the untrusted host virtual machine monitor; and the secondkey domain is a shared region of the memory shared by the untrusted hostvirtual machine monitor and each guest virtual machine managed by theuntrusted host virtual machine monitor.

Example 27 includes the processor of Example 23, where the guest controlstructure specifies a protected location of the memory where theprocessor may store the guest processor state information.

Example 28 includes the processor of Example 27, where the processor isfurther to: save the guest processor state information for the firstguest virtual machine in the protected location of the memory inresponse to an event triggering an exit condition of the first guestvirtual machine; and in response to receiving a resume command from theuntrusted host virtual machine monitor, the processor is further to:switch to the first key domain, retrieve the guest processor stateinformation for the first guest virtual machine from the protectedlocation of the memory, and execute the guest code image within thefirst key domain using the processor state information.

Example 29 includes the processor of Example 23, where the processor isfurther to: convert an exit condition of the first virtual machine to anexception.

Example 30 includes the processor of Example 23, where the processor isfurther to: decrypt an encrypted updated guest control structure toproduce an updated guest control structure; and enter the first guestvirtual machine using the updated guest control structure in response toreceiving an enter command to enter the first guest virtual machine.

Example 31 includes the processor of Example 23, where the processor isfurther to: decrypt an encrypted updated guest code image update toproduce an updated guest code image; and enter the first guest virtualmachine by executing the updated guest code image using the updatedguest control structure.

Example 32 includes the processor of Example 23, where the processor isfurther to: in response to receiving a second launch command to launch asecond guest virtual machine within the first key domain, the secondguest virtual machine to provide an agent to act on behalf of theuntrusted host virtual machine monitor within the first key domain, theprocessor is to: switch to the first key domain, decrypt the encryptedguest code image to produce an agent code image, decrypt the encryptedguest control structure to produce an agent control structure containingagent processor state information, and execute the agent code imagewithin the first key domain using the agent processor state information.

Example 33 includes the processor of Example 23, where the processor isfurther to: in response to receiving an enter command to enter the firstguest virtual machine using a modified guest control structure, executethe guest code image within the first key domain using second guestprocessor state information from the modified guest control structure.

Example 34 includes the processor of Example 23, where the processor isfurther to: determine a corresponding key domain key for a key domainidentifier for the first key domain, where the processor is to use thecorresponding key domain key to decrypt the encrypted guest controlstructure in response to receiving a load command to load the encryptedguest control structure into the memory, the load command comprising apointer to a physical address in the memory from which to load theencrypted guest control structure and the key domain identifier for thefirst key domain.

Note that the above processor can be implemented various needs.

Example 35 includes the processor of Examples 23-34 further comprising asystem on a chip (SoC) incorporated in a user equipment touch-enableddevice.

Example 36 is a system comprising a display, a memory, and the processorof one or more of the above Examples 23-34.

Example 37 includes at least one computer-readable medium comprisinginstructions that, when executed by a processor, cause a computer tosecurely execute a consumer workload in a public cloud environmentwithout exposing data or secrets of the consumer, the computer to:receive an encrypted key domain key, an encrypted guest code imageencrypted by a key domain key, and an encrypted guest control structureencrypted by the key domain key; issue a create command to the processorto create a first key domain, the first key domain comprising a regionof a memory to be encrypted by the key domain key; verify the encryptedguest control structure; and issue a launch command to the processor tolaunch a first guest virtual machine within the first key domain.

Example 38 includes the computer-readable media of Example 37, where theinstructions further cause the computer to: verify the encrypted guestcontrol structure by issuing a command to the processor to execute atleast one of a Hash Key Domain instruction and a VM Read instruction.

Example 39 includes the computer-readable media of Example 37, where theinstructions further cause the computer to: issue a resume command tothe processor to resume the first guest virtual machine.

Example 40 includes the computer-readable media of Example 37, where theinstructions further cause the computer to: intercept an interrupt; saveprocessor register information to a protected location of the memory inresponse to at least one of the interrupt and an exception thrown whenthe first guest virtual machine causes an exit condition; clear a firstprocessor register if the first processor register is not needed by anuntrusted host virtual machine monitor managing execution of the firstguest virtual machine; conditionally expose a second processor registerif the second processor register is needed by the untrusted host virtualmachine monitor; invoke the untrusted host virtual machine monitor; andexit the first guest virtual machine when the untrusted host virtualmachine monitor is invoked.

Example 41 includes the computer-readable media of Example 37, where theinstructions further cause the computer to: receive an encrypted updatedguest control structure, install the encrypted updated guest controlstructure in the memory, and verify the encrypted updated guest controlstructure; and issue an enter command to the processor to enter thefirst guest virtual machine using an updated guest control structure inresponse to verifying the encrypted updated guest control structure, theupdated guest control structure produced by the processor decrypting theencrypted updated guest control structure.

Example 42 includes the computer-readable media of example 41, where theinstructions further cause the computer to: receive an encrypted updatedguest code image; and install the encrypted updated guest code image inthe memory.

Example 43 includes the computer-readable media of example 37, where theinstructions further cause the computer to: determine whether a changeto the guest control structure is needed; verify, by the first virtualmachine, that the change to the guest control structure does notcompromise security of the first guest virtual machine; produce, by thefirst virtual machine, an encrypted updated guest control structureincorporating the change using the key domain key; and send, by thefirst virtual machine, the encrypted updated guest control structure toan untrusted host virtual machine monitor via a shared region of thememory shared by the untrusted host virtual machine monitor and thefirst guest virtual machine.

Example 44 includes the computer-readable media of example 43, where theinstructions further cause the computer to: install the encryptedupdated guest control structure in the memory; verify the encryptedupdated guest control structure; and issue an enter command to theprocessor to enter the first guest virtual machine using an updatedguest control structure in response to verifying the encrypted updatedguest control structure, the updated guest control structure produced bythe processor decrypting the encrypted updated guest control structure.

Example 45 includes the computer-readable media of example 44, where theinstructions further cause the computer to: determine whether the changeis needed to the guest control structure in response to a requestreceived from the first guest virtual machine.

Example 46 includes the computer-readable media of example 45, where theinstructions further cause the computer to: verify, by the first virtualmachine, that a second change to the guest code image included in therequest does not compromise security of the first guest virtual machine;produce, by the first guest virtual machine, an encrypted updated guestcode image incorporating the second change using the key domain key; andsend, by the first guest virtual machine, the encrypted updated guestcontrol image to the untrusted host virtual machine monitor via theshared region of the memory.

Example 47 includes the computer-readable media of example 46, where theinstructions further cause the computer to: receive the encryptedupdated guest code image, where executing the guest code image includesexecuting an updated guest code image produced by the processordecrypting the encrypted updated guest code image.

Example 48 includes the computer-readable media of example 37, where theinstructions further cause the computer to: verify an agent controlstructure included within the encrypted guest control structure; andissue a second launch command to the processor to launch a second guestvirtual machine within the first key domain using the agent controlstructure, the second guest virtual machine to provide an agent to acton behalf of the untrusted host virtual machine monitor within the firstkey domain.

Example 49 includes the computer-readable media of example 48, where theinstructions further cause the computer to: communicate a request tomodify the guest control structure of the first guest virtual machine tothe agent via a shared region of memory shared with the agent; modify,by the agent, the guest control structure of the first guest virtualmachine within the first key domain to produce a modified guest controlstructure of the first guest virtual machine in response to reading therequest from the shared region of memory; verify the modified guestcontrol structure of the first guest virtual machine; and issue an entercommand to the processor to enter the first guest virtual machine withinthe first key domain using the modified guest control structure uponverifying the modified guest control structure.

Example 50 includes the computer-readable media of example 48, where theinstructions further cause the computer to: communicate a request to theagent to retrieve a page from encrypted storage, where each page of theencrypted storage is encrypted by a storage key; decrypt, by the agent,the page using the storage key to produce a decrypted page; verify, bythe agent, the decrypted page; and install the decrypted page into thememory if the decrypted page is verified.

Example 51 includes the computer-readable media of example 50, where theinstructions further cause the computer to: copy, by the agent, thedecrypted page into the location of the memory if the agent has accessto a location in the memory into which the decrypted page is to beinstalled; and if the agent does not have access to a location in thememory into which the decrypted page is to be installed: re-encrypt, bythe agent, the page using the key domain key and a physical address ofthe location as a tweak to produce a re-encrypted page, and install, bythe untrusted host virtual machine monitor, the re-encrypted page intothe memory.

Example 52 includes the computer-readable media of example 48, where theinstructions further cause the computer to: communicate a request to theagent to move a page from encrypted memory to storage, where each pageof the encrypted memory is encrypted by the key domain key; decrypt, bythe agent, the page using the key domain key to produce a decryptedpage; verify, by the agent, the decrypted page; and if the decryptedpage is verified: re-encrypt, by the agent, the decrypted page with astorage key for the storage to produce a storage-encrypted page, move,by the agent, the storage-encrypted page to the storage, and provide, bythe agent, the storage-encrypted page to the untrusted host virtualmachine monitor.

Example 53 is a method to securely execute a consumer workload in apublic cloud environment without exposing data or secrets of theconsumer, the method including: receiving an encrypted key domain key,an encrypted guest code image encrypted by a key domain key, and anencrypted guest control structure encrypted by the key domain key;issuing a create command to a processor create a first key domain, thefirst key domain comprising a region of a memory to be encrypted by thekey domain key; verifying the encrypted guest control structure; andissuing a launch command to the processor to launch a first guestvirtual machine within the first key domain, where the launch commandincludes a pointer to an address of the encrypted guest controlstructure.

Example 54 includes the method of Example 53, where verifying theencrypted guest control structure includes verifying the encrypted guestcontrol structure by issuing a command to the processor to execute atleast one of a Hash Key Domain instruction and a VM Read instruction.

Example 55 includes the method of Example 53, further comprising:issuing a resume command to the processor to resume the first guestvirtual machine.

Example 56 includes the method of Example 53, further comprising:intercepting an interrupt; saving processor register information to aprotected location of the memory in response to at least one of theinterrupt and an exception thrown when the first guest virtual machinecauses an exit condition; clearing a first processor register if thefirst processor register is not needed by an untrusted host virtualmachine monitor managing execution of the first guest virtual machine;conditionally exposing a second processor register if the secondprocessor register is needed by the untrusted host virtual machinemonitor; invoking the untrusted host virtual machine monitor; andexiting the first guest virtual machine when the untrusted host virtualmachine monitor is invoked.

Example 57 includes the method of Example 53, further comprising:receiving an encrypted updated guest control structure, installing theencrypted updated guest control structure in the memory, and verifyingthe encrypted updated guest control structure; and issuing an entercommand to the processor to enter the first guest virtual machine usingan updated guest control structure in response to verifying theencrypted updated guest control structure, the updated guest controlstructure produced by the processor decrypting the encrypted updatedguest control structure.

Example 58 includes the method of Example 57, further comprising:receiving an encrypted updated guest code image; and installing theencrypted updated guest code image in the memory.

Example 59 includes the method of Example 53, further comprising:determining whether a change to the guest control structure is needed;verifying, by the first virtual machine, that the change to the guestcontrol structure does not compromise security of the first guestvirtual machine; producing, by the first virtual machine, an encryptedupdated guest control structure incorporating the change using the keydomain key; and sending, by the first virtual machine, the encryptedupdated guest control structure to an untrusted host virtual machinemonitor via a shared region of the memory shared by the untrusted hostvirtual machine monitor and the first guest virtual machine.

Example 60 includes the method of Example 59, further comprising:installing the encrypted updated guest control structure in the memory;verifying the encrypted updated guest control structure; and issuing anenter command to the processor to enter the first guest virtual machineusing an updated guest control structure in response to verifying theencrypted updated guest control structure, the updated guest controlstructure produced by the processor decrypting the encrypted updatedguest control structure.

Example 61 includes the method of Example 60, further comprising:determining whether the change is needed to the guest control structurein response to a request received from the first guest virtual machine.

Example 62 includes the method of Example 61, further comprising:verifying, by the first virtual machine, that a second change to theguest code image included in the request does not compromise security ofthe first guest virtual machine; producing, by the first guest virtualmachine, an encrypted updated guest code image incorporating the secondchange using the key domain key; and sending, by the first guest virtualmachine, the encrypted updated guest control image to the untrusted hostvirtual machine monitor via the shared region of the memory.

Example 63 includes the method of Example 62, further comprising:receiving the encrypted updated guest code image, where executing theguest code image includes executing an updated guest code image producedby the processor decrypting the encrypted updated guest code image.

Example 64 includes the method of Example 53, further comprising:verifying an agent control structure included within the encrypted guestcontrol structure; and issuing a second launch command to the processorto launch a second guest virtual machine within the first key domainusing the agent control structure, the second guest virtual machine toprovide an agent to act on behalf of the untrusted host virtual machinemonitor within the first key domain.

Example 65 includes the method of Example 64, further comprising:communicating a request to modify the guest control structure of thefirst guest virtual machine to the agent via a shared region of memoryshared with the agent; modifying, by the agent, the guest controlstructure of the first guest virtual machine within the first key domainto produce a modified guest control structure of the first guest virtualmachine in response to reading the request from the shared region ofmemory; verifying the modified guest control structure of the firstguest virtual machine; and issuing an enter command to the processor toenter the first guest virtual machine within the first key domain usingthe modified guest control structure upon verifying the modified guestcontrol structure.

Example 66 includes the method of Example 64, further comprising:communicating a request to the agent to retrieve a page from encryptedstorage, where each page of the encrypted storage is encrypted by astorage key; decrypting, by the agent, the page using the storage key toproduce a decrypted page; verifying, by the agent, the decrypted page;and installing the decrypted page into the memory if the decrypted pageis verified.

Example 67 includes the method of Example 66, further comprising:copying, by the agent, the decrypted page into the location of thememory if the agent has access to a location in the memory into whichthe decrypted page is to be installed; and if the agent does not haveaccess to a location in the memory into which the decrypted page is tobe installed: re-encrypting, by the agent, the page using the key domainkey and a physical address of the location as a tweak to produce are-encrypted page, and installing, by the untrusted host virtual machinemonitor, the re-encrypted page into the memory.

Example 68 includes the method of Example 64, further comprising:communicating a request to the agent to move a page from encryptedmemory to storage, where each page of the encrypted memory is encryptedby the key domain key; decrypting, by the agent, the page using the keydomain key to produce a decrypted page; verifying, by the agent, thedecrypted page; and if the decrypted page is verified: re-encrypting, bythe agent, the decrypted page with a storage key for the storage toproduce a storage-encrypted page, moving, by the agent, thestorage-encrypted page to the storage, and providing, by the agent, thestorage-encrypted page to the untrusted host virtual machine monitor.

In Example 69, a computer-readable medium including instructions is toperform the method of any of the above Examples.

In Example 70, a computer-readable medium including data is to be usedby at least one machine to fabricate at least one integrated circuit toperform the method of any one of the above Examples.

In Example 72, an apparatus comprises means for performing the method ofany one of the above Examples.

In Example 73, an apparatus to securely execute a consumer workload in apublic cloud environment without exposing data or secrets of theconsumer comprises: means for receiving an encrypted key domain key, anencrypted guest code image encrypted by a key domain key, and anencrypted guest control structure encrypted by the key domain key; meansfor issuing a create command to a processor create a first key domain,the first key domain comprising a region of a memory to be encrypted bythe key domain key; means for verifying the encrypted guest controlstructure; and means for issuing a launch command to the processor tolaunch a first guest virtual machine within the first key domain, wherethe launch command includes a pointer to an address of the encryptedguest control structure.

Example 74 includes the apparatus of Example 73, wherein the means forverifying the encrypted guest control structure comprises means forissuing a command to the processor to execute at least one of a Hash KeyDomain instruction and a VM Read instruction.

Example 75 includes the apparatus of Example 73, further comprising:means for issuing a resume command to the processor to resume the firstguest virtual machine.

Example 76 includes the apparatus of Example 73, further comprising:means for intercepting an interrupt; means for saving processor registerinformation to a protected location of the memory in response to atleast one of the interrupt and an exception thrown when the first guestvirtual machine causes an exit condition; means for clearing a firstprocessor register if the first processor register is not needed by anuntrusted host virtual machine monitor; means for conditionally exposinga second processor register if the second processor register is neededby the untrusted host virtual machine monitor; means for invoking theuntrusted host virtual machine monitor; and means for exiting the firstguest virtual machine when the untrusted host virtual machine monitor isinvoked.

Example 77 includes the apparatus of Example 73, further comprising:means for receiving an encrypted updated guest control structure,installing the encrypted updated guest control structure in the memory,and verifying the encrypted updated guest control structure; and meansfor issuing an enter command to the processor to enter the first guestvirtual machine using an updated guest control structure in response toverifying the encrypted updated guest control structure, the updatedguest control structure produced by the processor decrypting theencrypted updated guest control structure.

Example 78 includes the apparatus of Example 77, further comprising:means for receiving an encrypted updated guest code image; and means forinstalling the encrypted updated guest code image in the memory.

Example 79 includes the apparatus of Example 73, further comprising:means for determining whether a change to the guest control structure isneeded; means for verifying, by the first virtual machine, that thechange to the guest control structure does not compromise security ofthe first guest virtual machine; means for producing, by the firstvirtual machine, an encrypted updated guest control structureincorporating the change using the key domain key; and means forsending, by the first virtual machine, the encrypted updated guestcontrol structure to an untrusted host virtual machine monitor via ashared region of the memory shared by the untrusted host virtual machinemonitor and the first guest virtual machine.

Example 80 includes the apparatus of Example 79, further comprising:means for installing the encrypted updated guest control structure inthe memory; means for verifying the encrypted updated guest controlstructure; and means for issuing an enter command to the processor toenter the first guest virtual machine using an updated guest controlstructure in response to verifying the encrypted updated guest controlstructure, the updated guest control structure produced by the processordecrypting the encrypted updated guest control structure.

Example 81 includes the apparatus of Example 80, further comprising:means for determining whether the change is needed to the guest controlstructure in response to a request received from the first guest virtualmachine.

Example 82 includes the apparatus of Example 81, further comprising:means for verifying, by the first virtual machine, that a second changeto the guest code image included in the request does not compromisesecurity of the first guest virtual machine; means for producing, by thefirst guest virtual machine, an encrypted updated guest code imageincorporating the second change using the key domain key; and means forsending, by the first guest virtual machine, the encrypted updated guestcontrol image to the untrusted host virtual machine monitor via theshared region of the memory.

Example 83 includes the apparatus of Example 82, further comprising:means for receiving the encrypted updated guest code image, whereexecuting the guest code image includes executing an updated guest codeimage produced by the processor decrypting the encrypted updated guestcode image.

Example 84 includes the apparatus of Example 73, further comprising:means for verifying an agent control structure included within theencrypted guest control structure; and means for issuing a second launchcommand to the processor to launch a second guest virtual machine withinthe first key domain using the agent control structure, the second guestvirtual machine to provide an agent to act on behalf of the untrustedhost virtual machine monitor within the first key domain.

Example 85 includes the apparatus of Example 84, further comprising:means for communicating a request to modify the guest control structureof the first guest virtual machine to the agent via a shared region ofmemory shared with the agent; means for modifying, by the agent, theguest control structure of the first guest virtual machine within thefirst key domain to produce a modified guest control structure of thefirst guest virtual machine in response to reading the request from theshared region of memory; means for verifying the modified guest controlstructure of the first guest virtual machine; and means for issuing anenter command to the processor to enter the first guest virtual machinewithin the first key domain upon verifying the modified guest controlstructure.

Example 86 includes the apparatus of Example 84, further comprising:means for communicating a request to the agent to retrieve a page fromencrypted storage, where each page of the encrypted storage is encryptedby a storage key; means for decrypting, by the agent, the page using thestorage key to produce a decrypted page; means for verifying, by theagent, the decrypted page; and means for installing the decrypted pageinto the memory if the decrypted page is verified.

Example 87 includes the apparatus of Example 86, further comprising:means for copying, by the agent, the decrypted page into a location ofthe memory if the agent has access to the location in the memory intowhich the decrypted page is to be installed; and means forre-encrypting, by the agent, the page using the key domain key and aphysical address of the location as a tweak to produce a re-encryptedpage if the agent does not have access to a location in the memory intowhich the decrypted page is to be installed; and means for installing,by the untrusted host virtual machine monitor, the re-encrypted pageinto the memory if the agent does not have access to a location in thememory into which the decrypted page is to be installed.

Example 88 includes the apparatus of Example 84, further comprising:means for communicating a request to the agent to move a page fromencrypted memory to storage, where each page of the encrypted memory isencrypted by the key domain key; means for decrypting, by the agent, thepage using the key domain key to produce a decrypted page; means forverifying, by the agent, the decrypted page; re-encrypting, by theagent, the decrypted page with a storage key for the storage to producea storage-encrypted page if the decrypted page is verified; means formoving, by the agent, the storage-encrypted page to the storage; andmeans for providing, by the agent, the storage-encrypted page to theuntrusted host virtual machine monitor.

Understand that various combinations of the above examples are possible.

Note that the terms “circuit” and “circuitry” are used interchangeablyherein. As used herein, these terms and the term “logic” are used torefer to alone or in any combination, analog circuitry, digitalcircuitry, hard wired circuitry, programmable circuitry, processorcircuitry, microcontroller circuitry, hardware logic circuitry, statemachine circuitry and/or any other type of physical hardware component.Embodiments may be used in many different types of systems. For example,in one embodiment a communication device can be arranged to perform thevarious methods and techniques described herein. Of course, the scope ofthe present invention is not limited to a communication device, andinstead other embodiments can be directed to other types of apparatusfor processing instructions, or one or more machine readable mediaincluding instructions that in response to being executed on a computingdevice, cause the device to carry out one or more of the methods andtechniques described herein.

Embodiments may be implemented in code and may be stored on anon-transitory storage medium having stored thereon instructions whichcan be used to program a system to perform the instructions. Embodimentsalso may be implemented in data and may be stored on a non-transitorystorage medium, which if used by at least one machine, causes the atleast one machine to fabricate at least one integrated circuit toperform one or more operations. Still further embodiments may beimplemented in a computer readable storage medium including informationthat, when manufactured into a SoC or other processor, is to configurethe SoC or other processor to perform one or more operations. Thestorage medium may include, but is not limited to, any type of diskincluding floppy disks, optical disks, solid state drives (SSDs),compact disk read-only memories (CD-ROMs), compact disk rewritables(CD-RWs), and magneto-optical disks, semiconductor devices such asread-only memories (ROMs), random access memories (RAMs) such as dynamicrandom access memories (DRAMs), static random access memories (SRAMs),erasable programmable read-only memories (EPROMs), flash memories,electrically erasable programmable read-only memories (EEPROMs),magnetic or optical cards, or any other type of media suitable forstoring electronic instructions.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations therefrom. It is intended that the appendedclaims cover all such modifications and variations as fall within thetrue spirit and scope of this present invention.

What is claimed is:
 1. An apparatus comprising: a processor; and amemory coupled to the processor; wherein the processor is to execute anuntrusted host virtual machine monitor (VMM) to manage execution by theprocessor of at least one guest virtual machine (VM); the untrusted hostVMM is to cause the processor to create a key domain, the first keydomain comprising a region of the memory to be encrypted by a key domainkey that is inaccessible to the untrusted host VMM; the processor is toreceive an encrypted key domain key and decrypt the encrypted key domainkey to produce the key domain key; the untrusted host VMM is to causethe processor to launch a first guest VM within the key domain, whereinto launch the first guest VM within the key domain comprises switchingto the key domain, decrypting at least part of an encrypted domain imageto produce a guest control structure containing guest processor stateinformation and to produce a guest code image, and executing the guestcode image within the key domain using the guest processor stateinformation from the guest control structure; and the untrusted host VMMis to cause the processor to launch a second guest VM within the keydomain, the second guest VM to provide an agent to act on behalf of theuntrusted host VMM within the key domain, wherein to launch the secondguest VM within the key domain comprises switching to the key domain,decrypting at least part of the encrypted domain image to produce anagent code image and to produce an agent control structure containingagent processor state information, and executing the agent code imagewithin the key domain using the agent processor state information. 2.The apparatus of claim 1, wherein in response to an event triggering anexit condition of the first guest VM, the processor is to switch out ofthe key domain.
 3. The apparatus of claim 2, wherein the guest controlstructure specifies a protected location of the memory where theprocessor may store additional guest processor state information for thefirst guest VM; in response to the event triggering the exit conditionof the first guest VM, the processor is to save the additional guestprocessor state information for the first guest VM in the protectedlocation of the memory; and after the event triggering the exitcondition has been handled, the untrusted host VMM is to cause theprocessor to resume the first guest VM, wherein resuming the first guestVM comprises switching to the key domain, retrieving the additionalguest processor state information for the first guest VM from theprotected location of the memory, and executing the guest code imagewithin the key domain using the additional guest processor stateinformation.
 4. The apparatus of claim 3, wherein the guest code imagecomprises interrupt handler code to intercept an interrupt; theprocessor is to convert the exit condition of the first guest VM to anexception; the guest code image is to save processor registerinformation to the protected location of the memory in response to atleast one of the interrupt and the exception; the guest code image is toclear a first processor register if the first processor register is notneeded by the untrusted host VMM; the guest code image is toconditionally expose a second processor register if the second processorregister is needed by the untrusted host VMM; the guest code image is toinvoke the untrusted host VMM; and the first guest VM is to exit whenthe untrusted host VMM is invoked.
 5. The apparatus of claim 3, whereinthe untrusted host VMM is to receive an encrypted updated guest controlstructure, install the encrypted updated guest control structure in thememory, and verify the encrypted updated guest control structure; theprocessor is to decrypt the encrypted updated guest control structure toproduce an updated guest control structure; and in response to verifyingthe encrypted updated guest control structure, the untrusted host VMM isto cause the processor to enter the first guest VM using the updatedguest control structure.
 6. The apparatus of claim 5, wherein theuntrusted host VMM is further to receive an encrypted updated guest codeimage and to install the encrypted updated guest code image in thememory; the processor is to decrypt the encrypted updated guest codeimage update to produce an updated guest code image; and the processoris to enter the first guest VM by executing the updated guest code imageusing the updated guest control structure.
 7. The apparatus of claim 3,wherein the untrusted host VMM is to determine whether a change to theguest control structure is needed; the first guest VM is to verify thatthe change to the guest control structure does not compromise securityof the first guest VM; the first guest VM is to produce an encryptedupdated guest control structure incorporating the change using the keydomain key; and the first guest VM is to send the encrypted updatedguest control structure to the untrusted host VMM via a shared region ofthe memory shared by the untrusted host VMM and the first guest VM. 8.The apparatus of claim 7, wherein the untrusted host VMM is to installthe encrypted updated guest control structure in the memory; theuntrusted host VMM is to verify the encrypted updated guest controlstructure; the processor is to decrypt the encrypted updated guestcontrol structure to produce an updated guest control structure; and inresponse to verifying the encrypted updated guest control structure, theuntrusted host VMM is to cause the processor to enter the first guest VMusing the updated guest control structure.
 9. The apparatus of claim 1,wherein the untrusted host VMM is to communicate a request to modify theguest control structure of the first guest VM to the agent via a sharedregion of memory shared by the agent and the untrusted host VMM; inresponse to reading the request from the shared region of memory, theagent is to modify the guest control structure of the first guest VMwithin the key domain to produce a modified guest control structure ofthe first guest VM; the untrusted host VMM is to verify the modifiedguest control structure of the first guest VM; in response to verifyingthe modified guest control structure, the untrusted host VMM is to causethe processor to enter the first guest VM and execute the guest codeimage within the key domain using the modified guest control structure.10. The apparatus of claim 1, wherein the encrypted domain imagecomprises an encrypted version of the guest control structure; and theprocessor is to confirm integrity of the encrypted version of the guestcontrol structure.
 11. A processor to: execute an untrusted host virtualmachine monitor (VMM) to manage execution by the processor of at leastone guest virtual machine (VM); create a key domain in response to afirst command issued by the untrusted host VMM, the key domaincomprising a region of a memory to be encrypted by a key domain key thatis inaccessible to the untrusted host VMM; decrypt an encrypted keydomain key to produce the key domain key; launch a first guest VM withinthe key domain in response to a second command issued by the untrustedhost VMM, wherein to launch the first guest VM within the key domaincomprises to: switch to the key domain, decrypt at least part of anencrypted domain image to produce a guest control structure containingguest processor state information and to produce a guest code image, andexecute the guest code image within the key domain using the guestprocessor state information from the guest control structure; and inresponse to a third command issued by the untrusted host VMM, to launcha second guest VM within the key domain, the second guest VM to providean agent to act on behalf of the untrusted host VMM within the keydomain, wherein to launch the second guest VM within the key domaincomprises to: switch to the key domain, decrypt at least part of theencrypted domain image to produce an agent code image and to produce anagent control structure containing agent processor state information,and execute the agent code image within the key domain using the agentprocessor state information.
 12. The processor of claim 11, wherein theprocessor is further to: switch out of the key domain in response to anevent triggering an exit condition of the first guest VM.
 13. Theprocessor of claim 12, wherein the guest control structure specifies aprotected location of the memory where the processor may storeadditional guest processor state information for the first guest VM; andthe processor is further to: save the additional guest processor stateinformation for the first guest VM in the protected location of thememory in response to the event triggering the exit condition of thefirst guest VM; and resume the first guest VM after the event triggeringthe exit condition has been handled, wherein to resume the first guestVM comprises to: switch to the key domain, retrieve the additional guestprocessor state information for the first guest VM from the protectedlocation of the memory, and execute the guest code image within the keydomain using the additional guest processor state information.
 14. Theprocessor of claim 11, wherein the processor is further to: decrypt anencrypted updated guest control structure to produce an updated guestcontrol structure; and enter the first guest VM using the updated guestcontrol structure in response to receiving a command from the untrustedhost VMM to enter the first guest VM.
 15. The processor of claim 14,wherein the processor is further to: decrypt an encrypted updated guestcode image update to produce an updated guest code image; and enter thefirst guest VM by executing the updated guest code image using theupdated guest control structure.
 16. A method comprising: executing anuntrusted host virtual machine monitor (VMM) to manage execution of atleast one guest virtual machine (VM); in response to a first commandfrom the untrusted host VMM, creating, by the processor, a key domain,the key domain comprising a region of a memory to be encrypted by a keydomain key that is inaccessible to the untrusted host VMM; decrypting anencrypted key domain key to produce the key domain key; in response to asecond command from the untrusted host VMM, launching a first guest VMwithin the key domain, wherein launching the first guest VM comprises:switching to the key domain, decrypting at least part of an encrypteddomain image to produce a guest control structure containing guestprocessor state information and to produce a guest code image, andexecuting the guest code image within the key domain using the guestprocessor state information from the guest control structure; and inresponse to a third command issued by the untrusted host VMM, launchinga second guest VM within the key domain, the second guest VM to providean agent to act on behalf of the untrusted host VMM within the keydomain, wherein launching the second guest VM within the key domaincomprises: switching to the key domain, decrypting at least part of theencrypted domain image to produce an agent code image and to produce anagent control structure containing agent processor state information,and executing the agent code image within the key domain using the agentprocessor state information.
 17. The method of claim 16, furthercomprising: intercepting an interrupt; saving processor registerinformation to a protected location of the memory in response to atleast one of the interrupt and an exception thrown when the first guestVM causes an exit condition; clearing a first processor register if thefirst processor register is not needed by the untrusted host VMM;conditionally exposing a second processor register if the secondprocessor register is needed by the untrusted host VMM; invoking theuntrusted host VMM; and exiting the first guest VM when the untrustedhost VMM is invoked.
 18. The method of claim 16, further comprising:receiving an encrypted updated guest control structure, installing theencrypted updated guest control structure in the memory, and verifyingthe encrypted updated guest control structure; decrypting the encryptedupdated guest control structure to produce an updated guest controlstructure; and entering the first guest VM using the updated guestcontrol structure in response to verifying the encrypted updated guestcontrol structure.
 19. The method of claim 16, further comprising:determining whether a change to the guest control structure is needed;verifying, by the first guest VM, that the change to the guest controlstructure does not compromise security of the first guest VM; producing,by the first guest VM, an encrypted updated guest control structureincorporating the change using the key domain key; and sending, by thefirst guest VM, the encrypted updated guest control structure to theuntrusted host VMM via a shared region of the memory shared by theuntrusted host VMM and the first guest VM.
 20. The method of claim 19,further comprising: installing the encrypted updated guest controlstructure in the memory; verifying the encrypted updated guest controlstructure; decrypting the encrypted updated guest control structure toproduce an updated guest control structure; and entering the first guestVM using the updated guest control structure in response to verifyingthe encrypted updated guest control structure.
 21. The method of claim16, further comprising: verifying the agent control structure includedwithin the encrypted domain image.
 22. The method of claim 21, furthercomprising: communicating a request to modify the guest controlstructure of the first guest VM to the agent via a shared region ofmemory shared by the agent and the by the untrusted host VMM; modifying,by the agent, the guest control structure of the first guest VM withinthe first key domain to produce a modified guest control structure ofthe first guest VM in response to reading the request from the sharedregion of memory; verifying, by the untrusted host VMM, the modifiedguest control structure of the first guest VM; and entering the firstguest VM and executing the guest code image within the key domain usingthe modified guest control structure in response to verifying themodified guest control structure.
 23. At least one non-transitorycomputer-readable medium comprising instructions that, when executed bya processor of a computer, enable the computer to perform the method ofclaim 16.